ORGANIC  CHEMISTRY 


FOR  THE 


LABORATORY 


BY 


W.  A.  NOYES,  Ph.D., 

ti 
Professor  of  Chemistry  in  University  of  Illinois,  Urbana,  111. 


Second  Edition,  Revised  and  Enlarged 


EASTON,  PA. 
THE    CHEMICAL    PUBLISHING,,  CO. 

1911 


LONDON,    ENGLAND: 

WILLIAMS  &  NORGATE 

14  HENRIETTA  STREET,  COVENT  GARDEN,  W.  C. 


COPYRIGHT,  1897,  BY  EDWARD  HART. 
COPYRIGHT,  1911,  BY  EDWARD  HART. 


PREFACE  TO  SECOND  EDITION 


In  preparing  a  second  edition  of  this  book,  Chapters  on  the 
Analysis  of  Organic  Compounds,  on  General  Operations,,  on 
Ethers,  on  Hydroxy  and  Ketonic  Acids  and  on  Carbohydrates 
have  been  added,  and  thirty  new  preparations,  have,  been  included  . 
The  Chapters  in  the  book  have  also  been  rearranged .  to  corre- 
spond more  nearly  with  the  order  used. in  the  author's  text-book. 
It  is  hoped  that  this  rearrangement  ...will  .not  .interfere  with  the 
use  of  the  book  by  those  who  prefer  some  other  text-book  as 
the  basis  for  their  instruction..  . 

The  tables  for  nitrogen  have  been  recalculated  on  ^he=  basis 
of  modern  values  for  the  weight  of  one  liter  and  .for  the. co- 
efficient of  expansion  of  nitrogen.  Some  similar  tables  in  com- 
mon use  are  about  0.4  per,  cent,  in  error  becau.se,  old,  erroneous 
values  for  these  constants .  were  .used  in  their;,,  preparation- 

It  is  more  true  than  before  that  the  number  of  preparations 
given  is  too  great,  for  the  average  studerit,  to  complete^     To  meet,    . 
this  difficulty  classes  may  be  divided  into  groups  of  four  to  six 
students  and  each  group  be  required  tq  complete  nearly  all  .of     , 
the  preparations  in  the  book,  the  preparations   assigned  to  in-    . 
dividuals  being  different.     Each  individual-  oij  the  group  should 
be  expected  to  become  familiar  with  all  oft  the, fundamental  prin- 
ciples of  the  preparations  made  by  the  members  of  his  group. .    , 
By  this  method  the  knowledge  acquired, in  a  given  time  may  tje    . 
considerably  increased. . 

I  wish  -to  express  my  obligation  to  Professor  R.   S.   Cur,tiss,. ..,.,. 
Dr.  C.  G.  Derick  and  Dr.   L,.  H.  Cone  who,  have  .made  many,, 
valuable  suggestions  Ayith  regard  to  the  revision;  also  rto   Pro- 
fessor Edward  Hart,  wjio  furnished  , the  directions  for  -the, dis- 
tillation  of   wood   and    separation   of   the*  products    formed,    ?.s 
these  processes,  are  carried  out   in   his  laboratory.  , at   Lafayette 
College. 


304282 


PREFACE  TO  FIRST  EDITION 


The  science  of  organic  chemistry  rests,  for  its  experimental 
foundation,  on  the  preparation,  usually  by  synthetical  means, 
of  pure  compounds.  Without  a  knowledge,  based  on  personal 
experience  in  the  laboratory,  of  the  relations  involved  and  the 
methods  which  may  be  used  in  such  preparations,  no  satisfactory 
knowledge  of  the  science  can  be  acquired.  It  has  been  the  pur- 
pose of  the  author  in '  writing  this  book  to  classify  the  most 
important  of  the  laboratory  processes  which  have  been  used  in 
the  development  of  the  science  and  to  illustrate  them  by  con- 
crete examples. 

Two  distinct  purposes  have  been  kept  in  view.  The  first  has 
been  to  furnish  the  beginner  with  sufficiently  full  and  accurate 
directions  and  clear,  concise,  theoretical  explanations  of  pro- 
cesses which  have  been  found  successful  in  practical  laboratory 
experience.  The  second  object  has  been  to  furnish  the  more 
advanced  student  and  practical  worker  with  a  guide  which  will 
aid  him  in  the  selection  of  processes  which  are  likely  to  be  suc- 
cessful for  the  preparation  of  compounds  which  he  may  desire 
to  use. 

It  is  for  this  second  reason,  partly,  that  the  number  of  pre- 
parations given  is  considerably  greater  than  it  would  be  profitable 
for  the  average  student  to  prepare,  and  that  the  references  to 
the  literature  have  been  made  quite  full. 

The  student  who  uses  the  book  is  very  earnestly  advised  to 
begin  each  preparation  with  a  careful  study  of  the  directions 
given,  and  also  of  the  literature  of  the  subject.  For  the  time 
being,  he  should  make  himself  thoroughly  familiar  with  all  of  the 
important  relations  of  the  substance  with  which  he  is  working, 
and  with  other  methods  of  preparation  which  might  be  used. 
Comparatively  few  preparations  carefully  studied  in  this  way  will 
be  of  greater  value  than  a  much  larger  number  mechanically 
executed  by  simply  following  the  directions  of  the  book.  The 


PREFACE  V 

successful  student  must  be  able  to  use  intelligently  the  larger 
handbooks,  especially  that  of  Beilstein,  and  the  original  sources 
in  chemical  journals.  It  need  scarcely  be  remarked  that  a  satis- 
factory working  knowledge  of  organic  chemistry  cannot  be  ac- 
quired without  the  ability  to  use  German  books. 

In  some  cases  it  may  be  well  to  undertake  the  preparation  of 
analogous  substances  in  place  of  the  ones  which  are  given. 
The  majority  of  the  processes  described  should  be  viewed  from 
the  standpoint  that  they  are  applicable  to  many  other  similar 
cases,  though  slight  modifications  are  often  necessary  and  as  to 
that  the  student  should  satisfy  himself  by  examination  of  the 
literature  before  he  goes  on  with  his  work.  In  research  work 
chemists  very  often  help  themselves  by  a  careful  study  of  the 
properties  of  bodies  related,  or  analogous,  to  those  which  they 
wish  to  prepare,  and  the  habit  of  making  comparisons  of  this 
kind  is  very  valuable. 

It  is  not  the  intention  of  the  author  that  the  order  of  the 
book  should  be  necessarily,  or,  indeed,  usually  followed  by  the 
student.  He  has  a  very  firm  conviction  that  laboratory  work 
of  the  sort  provided  for  in  this  book  should  always  accompany 
the  lecture-room  or  text-book  work  in  organic  chemistry,  and 
that  the  frequent  lack  of  interest  in  the  subject  is  often  due  to  the 
fact  that  the  laboratory  work  is  given  a  year  or  two  after  the 
lectures,  or  that  it  is  omitted  altogether.  If  the  book  is  used 
in  conjunction  with  the  usual  course  of  lectures  to  beginners,  as 
it  is  hoped  that  it  may  be,  topics  will  naturally  be  selected  in  the 
same  general  order  as  that  followed  in  the  lectures  or  text-book. 

The  discussion  of  special  topics,  such  as  crystallization,  fil- 
tration, distillation,  distillation  under  diminished  pressure,  ex- 
traction, etc.  has  been  given  in  connection  with  preparations  when 
their  use  is  required.  Frequent  references  to  these  discussions 
are  given  elsewhere,  and  they  may  also  be  readily  found  by  means 
of  the  index. 

The  author  wishes  to  acknowledge  his  indebtedness  to  the 
somewhat  similar  works  of  Levy,  Gattermann,  Erdmann,  and  E. 
Fischer  for  many  suggestions;  also  to  a  little  book  by  Drs.  A. 


vi  PREFACE 

-  A.  No^es  'an'd  S.  P/Muttiken  'orn  the '"ClaTS  Reactions  of  ©rganic 
e  Substances/'  for  some  sagge'stion's"  in 'writing*  the  chapter  on  the 
L  qualitative '  exaniination  of  'organic  substances.  He"  also  'desires 
'  to" express  his  thanks  to  Mr.  W.  Er  Bark1,  whb*  prepared  the 

drawings  for  thevbbok,  a'nd"  td^Mr.  J.  JyKe'sslfer,  Jr.,  who  has 
'  tested  many  of  the  directions'  for  preparations^  in 'the' laboratory. 

I  wish  also  to'  express  my  smtere  thanks  to  Dr.  J.  Bishop  IHngle, 
"Who1  has'  read  :  carefully  all  of  the  proofs,  and  has  made  many 

valuable  suggestions.    * 


TABLE  OF  CONTENTS 


,    Chapter  I  PAGE 

ANALYSIS  OF  COMPOUNDS  OF  CARBONS    .  i 

Chapter  II 

GENERAL    OPERATIONS    : 25 

1.  Carbon  tetrachloride  and   aniline.,. 25 

2.  Urea,  phthalic  anhydride,  />-toluidine    29 

3.  Specific  gravity  of  alcohol 32 

4.  Distillation    of    wood    54 

Chapter  III 

HYDROCAREONS    38 

5.  Methane 41 

6.  Ethane 42 

7.  Ethylene    dibromide 44 

8.  Acetylene    47 

9.  Acetylene    49 

10.  Benzene    50 

11.  Cyclohexane    50 

12.  Paraxylene     54 

13.  Cymene     56 

14.  Diphenyl 56 

1 5.  Diphenyl    methane     57 

16.  Triphenyl  methane    58 

17.  Triphenylmethyl   and   triphenylmethyl   peroxide    60 

18.  Anthracene     60 

19.  Zinc    ethyl     -  61 

Chapter  IV 

ALCOHOLS   AND   PHENOLS    « 64 

20.  Absolute  ethyl   alcohol 67 

21.  Allyl    alcohol    .t : . . .  69 

4   22.  Paracresol 70 

23.  Benzyl    alcohol     72 

24.  Phenyl    methyl.  ,  carbinol     ,......-.    .....  .73 

25.  Triphenyl .  carbinol    . •,  •  •  •  •  74 

26.  Ethylene   glycol 75 

27.  Hydroquinone     . .      . 76 

28.  Alizarin     78 


Vlll  CONTENTS 

Chapter  V  PAGE 

ETHERS    81 

29.  Ethyl    ether    .    81 

30.  Anisole,   Phenyl   Methyl   ether 83 

31.  Phenyl  ether  of  salicyclic  acid   . .    84 

Chapter  VI 

ALDEHYDES,  KETONES  AND  THEIR  DERIVATIVES   86 

32.  Acetaldehyde     89 

33.  Acetone,    (Propanone)    92 

34.  Acetoxime    93 

35.  Semicarbazone  of  acetone   ' 94 

36.  Benzaldehyde    96 

37.  Benzoin    97 

38.  Benzil     98 

39.  Cinnamic   acid    • 99 

40  Phenyl  hydrazone  of  acetophenone    100 

41.  Benzophenone    101 

42.  Anthraquinone    103 

43.  Orthobenzoylbenzoic    acid 103 

44.  Xanthone    105 

Chapter  VII 

ACIDS    106 

45.  Formic   acid 115 

46.  Isovaleric  acid    1 16 

47.  Propionic  and  butyric  acids   119 

48.  Stearic  Acid    121 

49.  Camphoric  acid    ' 122 

50.  Benzoic  acid   125 

51.  o-  and  />-Nitrobenzoic  acids   • 126 

_  _  52.  Paratoluic    acid    • 131 

53.  Cinnamic   acid    133 

54.  Hydrocinnamic    acid    134 

55.  Malonic   ester    136 

56.  Succinic   acid 139 

57.  Phenolphthalein 141 

Chapter  VIII 

DERIVATIVES  OF  ACIDS    144 

58.  Acetyl  chloride    148 

59.  Acetic    anhydride 149 

60.  Succinic    anhydride    ' 150 

61.  Ethyl    acetic   ester    151 


CONTENTS  ix 

\ 

PAGE 

62.  Saponification   of  an  ester    152 

63.  Ethyl    succinic   ester    152 

64.  Benzoic   ethyl   ester    153 

65.  Phenyl   benzoate    154 

66.  Di-acetyl  tartaric  ethyl  ester  154 

67.  Acetamide    156 

68.  Acetanilide     157 

69.  Urea 158 

70.  Phenyl    sulphonamide    159 

71.  Phenyl   cyanide    161 

72.  Uric    acid     162 

Chapter  IX 

HYDROXY  AND  KETONIC  ACIDS    164 

73.  Salicylic   acid    165 

74.  Mendelic    acid    166 

75.  Acetoacetic    ester    170 

76.  Diacetyl    succinic    ester    175 

77.  Hydrocinnamic    acid    176 

78.  Antipyrine     178 

79.  Succinylosuccinic  ester t 180  • 

80.  Ethyl  ester  of      mesoxalic  acid      182 

Chapter  X 

CARBOHYDRATES  .    184 

81.  Fehling's  solution.     Inversion  of  sucrose   185 

82.  Maltose    and    dextrin    187 

83.  Specific  rotation  of  sucrose  and  invert  sugar  188 

84.  Schweitzer's   reagent.     Solution  of  cellulose    189 

85.  Preparation    of    furfural    from    a   pentose    190 

86.  Glucosazone 191 

87.  Levulinic    acid    192 

Chapter  XI 

HALOGEN  COMPOUNDS   194 

88.  Methyl    iodide    196 

89.  Ethyl  bromide    197 

90.  Para-dibrombenzene     198 

91.  Benzyl   chloride    199 

92.  Parabromtoluene    201 

93.  a-Brom-butyric    acid     203 

94.  Ethyl  ester  of  monobromomalonic  acid  205 

95.  Chloroform     206 

96.  lodoform     207 


X  CONTENTS 

Chapter  XII 

PAGE 

NITRO  COMPOUNDS 209 

-  -97.  Nitrobenzene     ...:...' 210 

98.  m-Dinitrobenzene 211 

99.  a-Nltronaphthalene     . . . 212 

100.  w-Nitro<toluene     212 

101.  />-Amino-0-Nitrotoluene    . . . . .  214 

102.  Meta-nitro-benzoic   acid    215 


Chapter  XIII 

AMINES    217 

•103.  Aniline ...'........  220 

104.  />-Amino-0-nitrotoluene 221 

105.  />-Phenylenediamine . .  223 

106.  Diethylamine 224 

107.  Isopropylamine 226 

108.  w-Phenyl-ethyl-amine -227 

109.  Aminomethylphen    229 

1 10.  Glycocoll     ' 231 

in.  Hippuric  acid 232 

1 12.  a-Aminoisobutyric    acid    233 

113.  Anthranilic    acid    v. 234 

114.  Indigo  from  anthranilic  acid 235 

115.  Aminomalonic    ester .......' 237 

1 16.  Skraup's  synthesis  of  quinoline 238 

117.  2,7-Dimethyl-4-ketodihydroquinazoline    or    2,7-Dimethyl-4-hy- 

droxyquinazoline 239 

1 18.  Collidinedicarboxyllic    ester    .'..•...'.;•..;-..'. '. .  240 

119.  Malachite   green 241 


Chapter  XIV 

DIAZO,  HYDRAZO,  NITROSO  AND  OTHER  NITROGEN  COMPOUNDS   244 

120.  Hydrazobenzene 248 

121.  Azobenzene ..........: : .  249 

122.  Benzene    diazonium   chloride    249 

123.  />-Aminoazobenzene     .....:....'. 250 

124.  />-Sulphobenzene-azo-a-riaphthylamine    ......:..:..:.:...:...  252 

125.  Helianthine    • .......*.. ....:...  253 

126.  Phenyl   hydrazine    J .  254 

127.  jS-Phenylhydroxylamine     255 


CONTENTS  XI 
Chapter   XV                                                        PAGE 

SULPHUR    COMPOUNDS 257 

128.  Sulphanilic    acid    ., 258 

129.  0-and-/>-Toluene    sulphonamides    259 

130.  Trimethylsulphonium    iodide     • 261 

131.  Thiophene     262 

Chapter  XVI 

QUALITATIVE  EXAMINATION  OF  CARBON  COMPOUNDS   264 

REAGENTS    ,                                                                 272 


Chapter  I 


ANALYSIS  OF  COMPOUNDS  OF  CARBONS 

Literature. — H.  Meyer:  Analyse  und  Konstitutionsermittelung  organi- 
scher  Verbindungen,  2  Auflage,  pp.  146-320;  Benedict:  Amer.  Chem.  J., 
23i  323  and  324;  J.  Am.  Chem.  Soc.,  ai,  389;  Mabery  and  Clymer:  Ibid, 
22,  213;  Dennstedt:  Anleitung  zur  vereinfachten  Elementaranalyse,  2 
Auflage,  1906,  also  Ber.,  4i>  600;  Z.  anal  chem.,  42,  41?- 

Determination  of  Carbon  and  Hydrogen. — The  apparatus  re- 
quired for  the  determination  of  carbon  and  hydrogen  in  a  com- 
pound containing  only  these  elements  or  these  elements  with 
oxygen  or  nitrogen,  or  both,  is  as  follows: 

1.  A  combustion  tube  10  to  12  cm.  longer  than  the  combustion 
furnace.     The  ends  should  be  cut  square  across  and  rounded, 
without  narrowing,  in  the  blast  flame,  heating  at  first  a  little 
distance  from  the  end.     The  tube  should  be  12  to   15  mm.  in 
internal  diameter,  of  infusible  glass  and  with  walls  about  2  mm. 
thick. 

2.  Copper  oxide,  granulated  or  wire  form. 

3.  A  copper  spiral  10  to  12  cm.  long,  two  spirals  2  to  3  cm. 
long,  and  one  5  to  6  cm.     The  two  short  spirals  should  fit  the 
tubes  closely,  the  other  two  loosely.     Each  spiral  is  made  by 
wrapping  pure  copper  wire  gauze  around  a  stiff  copper  wire, 
which  should  be  bent  to  a  loop  or  hook  at  one  end.     The  long 
copper  spiral  is  required  only  for  compounds  containing  nitrogen 
and  should  be  oxidized  superficially  by  holding  it  in  the  flame  of 
a  Bunsen  burner  and  then  reduced  by  plunging  it  while  hot  into 
a  test-tube  containing  about  one-half  cc.  of  pure  methyl  alcohol. 
The  tube  should  be  stoppered  till  the  spiral  has  cooled  and  the 
latter  dried  at  150°  and  placed,  while  hot,  in  a  desiccator. 

4.  A  105  mm.  U-tube  filled  with  calcium  chloride.     The  cal- 
cium chloride  should  be  in  granular  form  and  its  solution  in  water 
must  not  react  alkaline.     The  form  of  tube  shown  in  Fig.   I  is 
most  suitable.     The  bulb  A  is  so  constructed  that  the  water  col- 


ORGANIC   CHEMISTRY 


lecting  in  the  bulb  cannot  run  into  the  portion  of  the  tube  con- 
taining the  calcium  chloride.  The  rubber  stopper  at  B  must 
fit  tightly  and  should  be  cut  even  with  the  top  of  the  tube  and 


Pig.  i. 

covered  with  sealing  wax.  It  should  completely  fill  that  por- 
tion of  the  tube  above  the  side  arm  C  so  that  the  current  of  gas 
through  the  tube  will  be  direct.  A  small  plug  of  cotton  should 
be  placed  below  the  stopper  to  prevent  dust  from  the  calcium 
chloride  being  carried  out  mechanically.  Short  caps  of  rub- 
ber tubing  fitting  the  ends  of  the  U-tube  closely  and  closed 
with  glass  rods  should  be  provided  to  protect  the  tube  from  the 
air  when  not  in  use  and  similar  caps,  also,  for  the  potash 
bulbs.  The  caps  must  not  contain  loose  sulphur.  When  great 
accuracy  is  desired,  concentrated  sulphuric  acid  is  a  more  per- 
fect drying  agent  than  calcium  chloride.  See  Benedict,  Am. 
Chem.  J.,  23,  326. 

5.  Potash  bulbs,  best  of  the  improved  Geissler  form,  having 
diaphragms  within  each  bulb,  also  having  a  small  tube  to  be  filled 


ANALYSIS    OF    COMPOUNDS   OF    CARBONS  3 

with    granular    stick   potash    "ground   on."     Instead    of   potash 


B 


Fig.  2. 


bulbs  many  chemists  prefer  a  U-tube  filled  with  soda-iime. 
(Benedict:  Am.  Chem.  J.,  23,  323  and  334.)  The  portion  of 
the  U-tube  on  the  side  where  the  gases  leave  the  tube  should  be 
filled  with  calcium  chloride  for  3  to  4  cm.,  or  a  second  tube  con- 
taining glass  wool  and  a  little  sulphuric  acid  may  be  used  and 
weighed  with  the  soda-lime  tube. 

If  potash  bulbs  are  used,  they  are  filled  with  a  solution  of 
potassium  hydroxide  of  about  1.27  sp.  gr.  prepared  by  dissolv- 
ing 35  grams  of  potassium  hydroxide  in  100  cc.  of  water.  Only 
enough  of  the  solution  should  be  used  so  that  the  three  lower 
bulbs  are  filled  and  a  very  little  passes  into  the  fourth  bulb 
when  air  is  passed  through  the  system.  After  filling,  the  tube 
B,  through  which  the  solution  is  drawn,  it  should  be  carefully 
cleaned  both  within  and  without  before  putting  on  the  rubber 
caps.  It  is  safer  to  use  the  bulbs  only  twice  before  refilling  and 
in  no  case  should  they  be  used  after  acid  potassium  carbonate 
'separates  in  the  first  bulb. 


ORGANIC   CHEMISTRY 


6.  A  small  calcium  chloride  tube  and  a  piece  of  rubber  tub- 
ing to  connect  it  with  the  potash  tube  of  the  potash  bulbs. 

7.  Short    pieces   of    rubber   tubing    fitting   the   tubes    of    the 
potash  bulbs  and  of  the  U-tube  tightly.     The  tubing  should  have 
walls  about  2  mm.  thick.     If  white  tubing  is  used,  the  tubes 
should  be  soaked  in  a  solution  of  sodium  hydroxide  to  remove 
sulphur  and  thoroughly  washed  and  dried.     Red  or  black  tubing 
is    usually    preferred,       The    tubing 

should    be    stretched     and    carefully 
examined  for  minute  pores  or  holes. 

8.  Two  gasometers  or  large  bottles 
filled  respectively  with  air  and  oxygen. 
A  galvanized  iron  or  zinc  gasometer 
should   not   be   used   because   of   the 
danger    of    contaminating   the    gases 
with  hydrogen. 

9.  Two  sets  of  purifying  apparatus 
to  remove  carbon  dioxide  and  mois- 
ture   from    the   air   and   oxygen.     A 
suitable    form    is    shown    in    Fig.    3. 
The  space  around  the  inner  tube  is 
filled   with    soda-lime   and   the    inner 
tube,  which  passes  loosely  through  a 
larger  tube  that  separates  it  from  the 
soda-lime,  is  filled  with  pumice  dren- 
ched with  concentrated  sulphuric  acid 
(Benedict,   Am.   Chem,  J.,  23,   332). 
If  calcium  chloride  is  used  to  absorb 
the    water    from    the    combustion,    it 
should  be  used  last  in  the  purifying 
train,  while  if  sulphuric  acid  is  used 

for  the  former,  it  should  be  used  last  in  the  the  purifying  train, 
also.  Calcium  chloride  leaves  i.o  mg.  of  water  in  one  liter  of  a 
gas  dried  by  it  at  15°,  1.5  mg.  at  20°,  2.5  mg.  at  25°,  and  3.3  mg. 
at  30°,  while  concentrated  sulphuric  acid  leaves  only  about  0.002 
mg.  per  liter  at  15°  to  19°. 


Fig-  3- 


ANALYSIS   OF   COMPOUNDS   OF    CARBONS  5 

The  connections  from  the  gasometer  to  the  combustion  tube 
should  be  of  glass,  as  far  as  possible  with  only  short  connections 
of  rubber  tubing,  the  glass  tubes  being  brought  together  within 
the  rubber.  Moisture  and  other  gases  diffuse  through  India 
rubber,  and  there  is  some  danger  of  organic  matter  being  vol- 
atilized from  the  interior  of  a  long  rubber  tube. 

Between  the  purifying  apparatus  and  the  combustion  tube  a 
three-way  stop-cock  is  introduced  so  that  either  air  or  oxygen 
may  be  passed  through  the  tube  at  will  and  so  that  the  rate  of 
either  current  may  be  accurately  regulated. 

10.  A  porcelain  or  platinum  boat,  or,  for  volatile  substances, 
a  small  bulb  to  contain  the  substance  to  be  burned.  Liquids  which 
boil  above  250°  at  atmospheric  pressure  may  be  weighed  in  a 
boat,   but   should  be  weighed  immediately  before  burning.     If 
a  bulb  is  used,  it  should  have  a  not  too  narrow  capillary  stem,  at 
least  10  cm.  long  and  should  contain  a  small  piece  of  copper  oxide 
to  burn  the  portion  of  the  vapor  of  the  substances  remaining  in 
the  bulb.     The  bulb  is  filled  by  mearis  of  a  small  tube  drawn 
out  to  a  fine  capillary,  which  can  be  inserted  through  the  capillary 
of  the  bulb.     Or  it  may  be  filled  by  heating  the  bulb  and  dipping 
the  capillary  stem  in  the  liquid,  allowing  the  latter  to  be  drawn 
up    as    the   bulb    cools.     The   bulb   should,   of    course,   have   a 
capacity  of  only  0.3  to  0.5  cc.     It  should  be  placed  in  the  com- 
bustion tube  in  such  a  manner  that  by  heating  the  portion  of 
the  tube  where  the  bulb  rests,  the  liquid  can  be  forced  out  into 
some  of  the  copper  oxide  which  is  still  cold.     Without  this  pre- 
caution it  is  difficult  to  avoid  too  rapid  combustion. 

11.  Rubber  stoppers  fitting  the  combustion  tube,  soft  and  of 
the  best  quality.     It  is  well  to  soak  them  in  a  solution  of  sodium 
hydroxide   for  a  short  time  to   remove  sulphur.     They  should, 
of  course,  be  washed  clean  and  be  dry. 

12.  Two  asbestos  shields  to  place  over  the  combustion  tube 
at  the  ends  of  the  furnace  to  protect  the  rubber  stoppers. 


ORGANIC    CHEMISTRY 


The 


combustion  tube  is  filled  as  shown  in  Fig.  4.  If  the 
copper  oxide  is  to  be  used  for  the  first  time,  the 
tube  (without  the  reduced  copper  spiral)  should 
be  placed  in  the  furnace  and  heated  to  bright 
redness  in  a  slow  current  of  air  for  an  hour. 
If  the  copper  oxide  and  tube  have  been  used 
before,  heating  for  half  an  hour  will  suffice. 
The  portion  of  the  tube  where  the  substance  is 
to  be  placed  is  then  allowed  to  cool,  while  the 
entrance  of  moist  air  is  prevented  by  connecting 
the  exit  end  of  the  tube  with  a  calcium  chloride 
or  soda-lime  tube. 

The  potash  bulbs  and  U-tube  are  carefully 
wiped  with  a  clean  dry  cloth,  and  should  be 
allowed  to  stand  in  or  near  the  balance  (with  the 
caps  on)  for  an  hour  before  weighing.1  They 
are  weighed  zvithout  the  caps.  The  accuracy 
+  of  the  weighing  may  be  increased  by  using  a 
*  counterpoise  of  exactly  the  same  character  and 
kept  beside  the  U-tube  and  potash  bulbs  during 
all  of  the  operations.  If  proper  care  is  taken 
and  good  common  sense  is  used  with  regard  to 
the  conditions  of  weighing  and  methods  of  hand- 

s         ling   a   reasonable    degree    of   accuracy   can    be 

^        secured  without  this  precaution. 

When  the  combustion  tube  has  cooled  suffi- 
ciently, the  reduced  copper  spiral  is  placed  in 
the  front  part  of  the  tube  (if  the  substance  to 
be  analyzed  contains  nitrogen)  and  the  rubber 
stopper  carrying  the  calcium  chloride  U-tube  is 

5        inserted  and  the  potash  bulbs  connected  to  the 

^  U-tube  and  the  calcium  chloride  or  soda-lime 
tube  connected  to  the  exit  of  the  potash  bulbs 
to  protect  them  from  moisture  and  carbon  dioxide 

1  A  little  radium  in  the  balance  case  will  dissipate  electric 
charges  which  are  sometimes  troublesome  (T.  W.  Richards). 


ANALYSIS    OF    COMPOUNDS   OF   CARBONS  7 

from  the  air.  In  forcing  the  tube  of  the  U-tube  through  the  stopper 
and  in  making  the  connections  the  tube  and  bulbs  should  always  be 
grasped  by  the  small  tube  which  is  to  be  forced  into  the  stopper 
or  connection,  as  the  apparatus  is  fragile.  The  glass  tubes  should 
be  brought  together  within  the  connections  and  should  be  secured 
against  leakage  by  tying  with  fine  copper  wire,  thread  or  by  a 
rubber  thread  made  by  breaking  a  rubber  band.  One  of  the 
greatest  dangers  of  the  whole  process  is  that  of  slight  leaks 
in  the  connections.  After  all  of  the  connections  are  com- 
plete, a  test  for  leaks  may  be  made  by  admitting  oxygen  from 
the  rear  and  after  stopping  the  current,  watching  to  see  if  the 
solution  in  the  potash  bulbs  falls  back  from  the  level  to  which  it 


Fig-  5- 

is  forced.  The  test  is  not  always  satisfactory,  especially  when  a 
part  of  the  tube  is  warm. 

When  the  absorption  train  has  been  properly  connected  to 
the  front  end  of  the  tube  the  stopper  at  the  rear  is  removed, 
the  oxidized  copper  spiral  taken  out  and  put  into  a  dry  test  tube, 
which  is  immediately  stoppered,  the  boat  or  bulb  containing 
0.15  to  0.25  grams  of  the  substance  introduced  and  the  oxidized 
spiral  replaced  with  the  least  possible  exposure  to  the  air,  since 
copper  oxide  is  hygroscopic.  The  rear  stopper  connecting  with 
the  purifying  trains  for  oxygen  and  air  is  then  inserted  and  the 
test  for  leaks  referred  to  above,  is  made.  • 

If  no  leak  is  found,  light  the  first  six  or  seven  burners  and 
turn  them  very  low,  either  individually,  or  by  means  of  the 
stop-cock  regulating  the  gas  supply  for  the  whole  furnace. 


8  ORGANIC   CHEMISTRY 

Turn  these  burners  up  a  little  once  in  two  minutes,  by  trie  watch, 
till  the  front  portion  of  the  tube  shows  faint  redness,  then  pro- 
ceed slowly  with  the  burners  further  back  toward  the  substance. 
At  the  same  time  light  one  burner  under  the  spiral  in  the  rear  of 
the  boat  or  bulb,  and  start  a  very  slow  current  of  oxygen 
through  the  tube.  The  portion  of  the  tube  in  the  neighborhood 
of  the  boat  must  be  heated  very  gradually  in  all.  cases  so  that 
the  substance  is  slowly  volatilized  and  burned. 

In  the  Berlin  laboratory  a  clock-work  device  has  been  arranged 
to  move  some  -burners  very  slowly  under  the  substance  and  se- 
cure slow  and  uniform  burning.  A  porcelain  boat  with  twelve 
compartments  is  used  to  hold  the  substance. 

Substances  vary  greatly  in  the  care  which  must  be  exercised 
in  burning  them.  The  bubbles  should  never  pass  the  potash  bulbs 
more  rapidly  than  they  can  be  counted.  Explosive  substances  and 
sometimes  other  substances  may  be  mixed  in  the  boat  with  line 
copper  oxide  to  advantage.  The  copper  oxide  to  be  used  for 
this  purpose  should  be  ignited  in  a  porcelain  or  copper  crucible 
and  cooled  in  a  desiccator.  Salts  of  barium,  calcium  or  the  alka- 
lies should  be  mixed  with  a  mixture  of  lead  chromate  and 
potassium  pyrochromate  which  has  been  fused  and  pulverized. 
This  will  decompose  the  metallic  carbonate  formed  and  expel 
the  carbon  dioxide. 

When  the  combustion  of  the  substance  is  nearly  finished  the 
current  of  gas  passing  into  the  potash  bulbs  will  usually  slaken 
and  the  portion  of  the  tube  containing  the  boat  may  be  brought  to 
full  redness  while  the  current  of  oxygen  may  be  considerably  in- 
creased as  the  reduced  copper  is  being  reoxidized.  At  the  same 
time  the  flames  under  the  reduced  copper  spiral  should  be  low- 
ered to  prevent  undue  oxidation  of  the  latter.  Water  sometimes 
condenses  in  the  front  end  of  the  combustion  tube.  This  may  be 
driven  on  into  the  calcium  chloride  tube  by  very  careful  warm- 
ing with  a  flame  or  by  holding  a  hot  tile  from  the  furnace  near 
the  tube.  The  current  of  oxygen  is  continued  till  it  can  be 
detected  with  a  glowing  splinter  at  the  end  of  the  protecting 
calcium  chloride  tube.  It  must  then  be  displaced  by  dry  air 


ANALYSIS   OF   COMPOUNDS   OF   CARBONS  9 

from  the  second  gasometer,  to  avoid  the  error  which  would  re- 
sult if  the  calcium  chloride  tube  and  potash  bulbs  were  weighed 
full  of  oxygen  instead  of  air.  The  passage  of  300  to  400  cc.  of 
air  will  usually  be  enough.  It  is  passed  till  a  glowing  splinter 
no  longer  shows  oxygen  at  the  exit.  Not  more  than  one-half 
liter  to  one  liter  of  oxygen  should  be  needed,  if  properly  used. 
The  use  of  excessive  amounts  of  oxygen  or  air  is  to  be  avoided. 

When  the  operation  is  complete  the  calcium  chloride  tube  and 
potash  bulbs  are  disconnected,  protected  at  once  with  the  rubber 
caps,  wiped  as  before  and  placed  near  the  balance  for  an  hour 
before  weighing. 

The  hydrogen  is  calculated  from  the  weight  of  the  water  by 
the  factor  0.1119,  the  carbon,  most  easily  by  taking  3/11  of  the 
weight  of  the  carbon  dioxide. 

For  substances  containing  sulphur,  lead  chromate,  fused  and 
granulated,  is  used  in  place  of  copper  oxide.  For  substances 
containing  halogens  a  spiral  of  silver  gauze  or  silver  foil,  heated 
only  moderately,  is  inserted  in  place  of  the  reduced  copper  spiral, 
or  a  boat  containing  reduced  silver  in  the  form  of  a  powder  may 
be  used. 

Determination  of  Nitrogen  by  the  "Absolute"  Method 

Literature.— Johnson  and  Jenkins:  Am.  Chem.  J.,  2,  27;  Schiff:  Ber.,i3, 
885;  Bradley  and  Hale:  J.  Am.  Chem.  Soc.,  3Q»  1090. 

For  the  determination  of  nitrogen  by  the  absolute  method 
the  substance  is  burned  in  a  current  of  carbon  dioxide,  the 
nitrogen  is  swept  out  into  an  azotometer  filled  with  a  solution  of 
potassium  hydroxide  and  the  nitrogen  is  measured. 

The  combustion  tube  may  be  prepared  in  exactly  the  same  man- 
ner (p.  6)  as  for  the  determination  of  oxygen  and  hydrogen,1 
though  some  prefer  to  seal  the  tube  at  the  rear  and  put  in  that 
end  a  layer  of  magnesite  15  cm.  in  length,  followed  by  a  copper 
spiral,  a  layer  of  copper  oxide,  the  substance  mixed  with  copper 
oxide,  a  long  layer  of  copper  oxide  and  the  reduced  copper 
spiral. 

1  A  tube  used  for  nitrogen  should  not  afterwards  be  used  for  carbon  and  hydrogen, 
unless  it  has  been  burned  out  in  a  current  of  oxygen. 


IO  ORGANIC   CHEMISTRY 

If  an  open  tube  of  the  same  form  used  for  the  determination 
of  carbon  and  hydrogen  is  employed,  the  necessary  carbon  dioxide 
may  be  generated  by  heating  about  25  grams  of  acid  sodium 
carbonate  in  a  hard  glass  tube  protected  by  a  sheet  iron  mantel. 
Between  the  generating  tube  and  the  combustion  tube  a  small  bulb 
tube  of  the  form  shown  in  Fig.  6  should  be  introduced  to  col- 
lect the  water  which  comes  from  the  acid  carbonate. 

The  carbon  dioxide  may  also  be  generated  in  the  apparatus 
shown  in  Fig.  7.  A  is  a  200  cc.  Kjeldahl  flask  with  a  long  neck. 
In  it  are  placed  20  grams  of  acid  sodium  carbonate  and  50  cc. 
of  water.  B  is  a  separatory  funnel  having  a  long  stem,  all  of  it 
below  C  of  capillary  tubing,  except  the  bulb  at  D,  which  has  a 


Fig.  6. 

capacity  of  4-5  cc.  This  capillary  tube  should  have  an  internal 
diameter  of  not  more  than  2  mm.  The  separatory  funnel  should 
contain  30  cc.  of  sulphuric  acid  (one  part  of  concentrated  acid 
to  one  of  water  by  volume)  which  should  be  drawn  into  it  through 
the  capillary  stem  so  that  there  will  be  no  air  below  the  stop- 
'cock.  The  capillary  stem  of  the  funnel  should  not  dip  below 
the  surface  of  the  solution  and  should  be  at  least  30  cm.  long  to 
furnish  enough  pressure  so  that  the  gases  can  be  readily  forced 
through  the  combustion  tube  and  into  the  azotometer.  While  the 
front  portion  of  the  combustion  tube  is  being  heated  the  solu- 
tion in  the  generator  is  boiled  very  gently  for  about  10  minutes, 
causing  a  slow  evolution  of  carbon  dioxide,  which  will  expel 
the  air  from  the  water  and  flask.  The  exit  tube  is  then  closed 
tightly  with  a  short  piece  of  rubber  tubing  and  pinch-cock  and  the 


ANALYSIS   OF   COMPOUNDS  OF   CARBONS 


II 


stop-cock  of  the  separatory  funnel  opened  very  cautiously  so  that 
the  acid  may  drop  in  very  slowly.  As  soon  as  the  apparatus 
is  cooled  a  little  the  exit  tube  is  connected  with  the  bulb  tube 
(Fig.  6)  and  the  latter  to  the  rear  end  of  the  combustion  tube, 


Pig-  7- 

into  which  the  substance  has  meantime,  been  introduced  in  a 
boat  or  bulb,  as  described  for  the  determination  of  carbon  and 
hydrogen.  The  other  end  of  the  combustion  tube  is  connected 
with  the  azotometer  shown  in  Fig.  8.  The  mercury  in  the  lower 


12  ORGANIC  -CHEMISTRY 

end  of  the  azotometer  should  come  about  I  cm.  above  the  entrance 
of  the  side  tube  through  which  the  gases  are  delivered.  The 
potash  solution  is  prepared  by  dissolving  100  grams  of  stick  potash 
in  160  cc.  of  water  giving  a  solution  which  contains  approxi- 
mately 40  per  cent,  of  potasium  hydroxide.  At  this  point  in  the 
operation  the  stop-cock  at  the  top  of  the  azotometer  is  opened 
and  the  bulb  lowered  so  that  nearly  all  of  the  potash  solution  is  in 
the  bulb.  While  the  front  portion  of  the  combustion  tube  is  hot 


Fig.  8. 

and  after  all  of  the  connections  have  been  made  as  described,  the 
generation  of  a  moderate  current  of  carbon  dioxide  is  continued 
by  dropping  the  acid  into  the  generator  very  slowly  during  ten 
or  fifteen  minutes.  The  potash  solution  is  then  brought  to  the 
top  of  the  azotometer,  the  stop-cock  closed,  the  bulb  lowered  again 
to  reduce  the  pressure  and  the  carbon  dioxide  entering  the 
azotometer  examined  to  see  if  it  is  free  from  air  and  completely 
absorbed  by  the  potassium  hydroxide.  During  this  part  of  the 
operation  great  care  must  be  taken  that  the  substance  does  not 
become  warm  enough  so  that  any  of  it  volatilizes  or  decom- 


ANALYSIS   OF    COMPOUNDS   OF    CARBONS  13 

poses.  If  the  test  is  satisfactory,  then  the  combustion  may  be 
carried  out  essentially  as  in  the  determination  of  carbon  and 
hydrogen.  During  the  combustion  the  current  of  carbon  dioxide 
should  be  very  slow  indeed.  It  is  continued  till  the  portion  of 
the  tube  containing  the  substance  has  been  heated  to  bright  red- 
ness and  no  more  nitrogen  passes  into  the  azotometer.  After 
the  combustion  is  completed  the  azotometer  is  placed  in  a  room 
of  uniform  temperature  and  the  volume  of  the  nitrogen  is  read 
after  half  an  hour  or  an  hour.  During  this  time  the  bulb  con- 
nected with  the  side  tube  should  be  brought  to  the  level  of  the 
top  of  the  potash  solution  in  the  azotometer  so  that  the  gas  will 
be  under  atmospheric  pressure  and  less  likely  to  change  its  vol- 
ume by  leakage.  It  hardly  need  be  said  that  the  stop-cock  must 
be  .carefully  lubricated  with  a  viscous  lubricant.  It  is  also  well 
to  have  a  little  of  the  potash  solution  in  the  tube  above  the 
stop-cock. 

The  azotometer  should  be  carefully  calibrated.  This  may  be 
done  by  attaching  to  the  lower  end,  at  B,  a  rubber  tube,  pinch- 
cock  and  delivery  tip  such  as  is  used  with  a  Mohr's  burette. 
The  first  two  or  three  cubic  centimeters  at  the  top  should  be 
calibrated  with  the  burette  filled  with  a  potassium  hydroxide  so- 
lution of  about  the  same  strength  as  that  used  in  the  analysis, 
since  the  form  of  meniscus  of  such  a  solution  is  quite  different 
from  that  of  pure  water.  The  specific  gravity  of  the  solution 
used  must,  of  course,  be  known,  accurately.  For  the  rest  of  the 
azotometer  pure  water  may  be  used  for  the  calibration,  since  it 
is  the  value  of  the  intervals  between  successive  marks  which  is 
required.  For  the  calculation  of  the  volume  from  the  weights 
of  water  see  p.  33. 

In  reading  the  volume- of  the  nitrogen  the  level  of  the  potash 
solution  in  the  bulb  must  be  brought  to  the  level  of  the  top  of 
the  solution  in  the  azotometer  so  that  the  nitrogen  will  be  at  at- 
mospheric pressure.  At  the  time  of  this  reading  the  pressure 
of  the  air  is  determined  by  means  of  a  barometer,  whose  reading 
should  be  corrected  to  zero. 

For  a  pressure  of  760  mm.  the  correction  which  is  to  be  sub- 
tracted from  the  reading  of  the  barometer  is : 


14  ORGANIC   CHEMISTRY 

Correction  for  Correction  for 

f°  glass  scale  brass  scale 

5  0.7  0.6 

10  1.3  1.2 

15  2.0  1.9 

20  2.7  2.5 

25  3-3  3-1 

3°  4-0  3-7 

35  4-7  4-3 

A  change  of  7.6  mm.  in  the  pressure  causes  a  change  of  one  per 
cent,  -in  the  correction.  Thus  if  the  pressure  read  is  730  mm.  at 
25°  the  correction  is  to  be  diminished  by  4  per  cent,  and  becomes 
3.2  for  a  glass  scale.  This  secondary  correction  is  too  small  to 
be  of  practical  importance  for  gases  at  atmospheric  pressure. 

The  temperature  is  determined  by  means  of  a  thermometer 
placed  beside  the  azotometer. 

The  weight  of  the  nitrogen  may  be  calculated  by  the  formula : 

Wt.  in  grams  =  0.0012507  V  X      ^^    X 

=  0.00449  V  X 

V  =  =  Volume  in  cubic  centimeters 
/    =  temperature  of  the  gas 
p  —  Barometric  pressure 

p    =  Aqueous  pressure  of  a  40  per  cent,  solution  of 
potassium  hydroxide. 

TABLE  OF  VAPOR  PRESSURE 

Aqueous  pressure  in  millimeters  of  pure  water  and  of  a  40  per  cent, 
solution  of  potassium  hydroxide2 

Pure        40  #  Pure        40$  Pure          40* 

1°          H2O        KOH  t°  H2O        KOH  t°  H2O          KOH 

0  4.6  2.6  12  I0*.5  5.8  24  22.2  II.7 

1  4-9  2-8  13  II- 2  6.1  25  23.5  12.4 

2  5-3  3-°  14  ii. 9  6.5  26  25.0  13.1 

3  5-7  3-2  15  12.7  6.9  27  26.5  13.6 

4  6.1  3.4  16  13.6  7.4  28  28.1  14.7 

5  6.5  3.6  17  14.4  7.8  29  29.8  15.5 

6  7-0  3-9  l8  154  8.3  30  31.6  16.4 

7  7-5  4-1  19  l6-4  8.9  31  33.4  17.3 
8.0  4.4  20  17.4  9.3  32  35.4  18.3 

9        8.6        4.7  21         18.5        9-9  33        37-4        18.4 

10  9.2        5.1  22         19.7       10.5  34        39.6        20.5 

11  9-8        5-4  23        20.9       ii. i  35        41.9        21.5 

1  The  fraction ——  would  be  more  accurate,  as  nitrogen  is  not  an  ideal  gas,  but 

the  error  of  the  usual  formula  is  only  one  part  in  1300  at  25°. 

2  Prepared  by  interpolation  from  the  Landolt-Bernstein-Meyerhoffer  Tabellen,  pp. 
71  and  723. 


ANALYSIS   OF    COMPOUNDS   OF    CARBONS  15 

REDUCTION  OF  CUBIC  CENTIMETERS  OF  NITROGEN  TO  GRAMS 


s  (l  +  0.003676)760 

/° 

0.0 

O.I 

0.2 

0.3 

0.4 

0.5 

0.6 

0.7 

0.8 

0.9 

0 

"21634 

618 

603 

587 

57i 

555 

539 

523 

507 

491 

I 

475 

459 

443 

427 

411 

396 

380 

364 

348 

332 

2 

3i6 

300 

284 

268 

252 

236 

221 

205 

I89 

i/4 

3 

158 

142 

127 

in 

095 

079 

064 

048 

032 

017 

4 

OOI 

—986 

—970 

—954 

—939 

-923 

-907 

-892 

-876 

—860 

5 

6*20844 

829 

813 

798 

'  782 

767 

751 

735 

719 

703 

6 

687 

672 

656 

641 

625 

609 

594 

578 

563 

547 

7 

531 

5i6 

500 

484 

469 

453 

437 

422 

406 

39i 

S 

375 

360 

344 

329 

313 

298 

282 

267 

251 

236 

9 

221 

205 

190 

174 

159 

143 

128 

112 

097 

082 

10 

066 

051 

035 

020 

005 

-989 

-974 

-968 

-943 

—928 

II 

"19913 

897 

882 

867 

852 

836 

821 

806 

791 

776 

12 

759 

744 

729 

7H 

699 

684 

679 

653 

638 

623 

'3 

607 

592 

577 

562 

547 

53i 

5i6 

501 

486 

47i 

M 

455 

440 

425 

410 

395 

380 

365 

350 

335 

320 

15 

3°4 

289 

274 

259 

244 

229 

214 

I99 

184 

169 

16 

153 

138 

123 

108 

093 

078 

063 

048 

033 

018 

17 

002 

-987 

—972 

-957 

—942 

—927 

—912 

-897 

—882 

-867 

18 

"18852 

837 

822 

807 

792 

777 

762 

747 

732 

7i7 

r9 

703 

688 

673 

658 

643 

628 

613 

598 

583 

568 

20 

553 

538 

523 

508 

493 

478 

464 

449 

434 

419 

21 

405 

39° 

375 

360 

345 

33i 

3i6 

301 

286 

271 

22 

257 

242 

227 

213 

198 

183 

168 

154 

139 

124 

23 

109 

095 

080 

066 

051 

036 

02  1 

007 

—992 

—977 

24 

"17962 

947 

932 

918 

903 

888 

874 

859 

845 

830 

25 

816 

80  1 

786 

772 

757 

742 

728 

713 

699 

684 

26 

670 

655 

641 

626 

612 

597 

583 

568 

554 

539 

27 

524 

5to 

496 

481 

467 

452 

438 

423 

409 

394 

28 

379 

364 

350 

335 

321 

306 

292 

2/8 

263 

249 

29 

235 

220 

206 

191 

177 

163 

148 

134 

119 

105 

30 

091 

077 

063 

048 

034 

020 

005 

—991 

—977 

-962 

3i 

"16947 

933 

919 

904 

889 

875 

86  1 

847 

833 

819 

32 

804 

790 

776 

762 

747 

733 

719 

704 

690 

675 

33 

66  1 

647 

633 

6i9 

604 

590 

576 

562 

548 

534 

34 

519 

505 

491 

477 

462 

448 

434 

420 

406 

392 

1  From  Frankland's  Water  Analysis,  corrected  for  the  modern  values  for  the  weight 
and  coefficient  of  expansion  of  nitrogen. 


i6 


ORGANIC   CHEMISTRY 


The  accompanying  table  will  be  found  more  convenient  foi-  the 
calculations.  Add  together  the  logarithm  corresponding  to  the 
temperature  taken  from  the  table,  the  logarithm  of  the  volume 
and  the  logarithm  of  (P  —  p).  The  sum  will  be  the  logarithm 
of  the  weight  of  nitrogen  in  milligrams. 

WEIGHT  OF  NITROGEN  IN  ONE  CUBIC  CENTIMETER  OF  THE 

GAS  MEASURED  OVER  WATER 

If  the  gas  is  measured  over  a  40  per  cent,  solution  of  potassium  hydroxide, 
add  to  the  barometric  reading  the  difference  between  the  aqueous  pressure 
of  pure  water  and  that  of  the  potassium  hydroxide  solution  at  the  given 
temperature.  The  table  is  based  on  1.2507  as  the  weight  of  one  cubic  centi- 
meter of  dry  nitrogen  at  o°  and  760  mm. 

tP      721     724     727        730     733     736         739     742     745 

10        1.130     1.135     1.139  1.144     1.149     I-I54  1-158     1.163     1-168 


11  1.125  1.129  1.134 

12  I.I2O  I.I24  I.I29 

13  I.H5  T.II9  LI24 

14  i.uo  1.114  1.119 

15  I.I05  I.I09  I.II4 

16  1.099  I-I°3  I-2°8 

17  1.094  1.098  1.203 

18  1.089  1.093  1.098 

19  1.084  1.088  1.093 

20  1.079  1.083  i. 088 

21  1.074  1.078  1.082 

22  1. 068  1.072  1.076 

23  I.O62  1.067  I.O7I 

24  I.O57  1 .06 1  1. 066 

25  I.05I  1.056  1. 060 

26  1.056  1.050  1.054 

27  1.040  1.044  1.048 

28  1.034  1.038  1.042 

29  I.O28  I.O32  1.036 

30  1.022  1.026  I.03I 

31  I.OI5  I.O2O  I.O24 

32  1.009  LOI4  I.OlS 

33  1.003  1.008  i. 012 

34  0.996  i.ooi  1.005 

35  0.990  0.995  0.999 


1.139 

1.  144 

I.I48 

I-I53 

1.158 

1.162 

1.134 

I-I39 

I.I43 

I.I48 

1.  153 

I-I57 

1.129 

I-I34 

I.I38 

1.  143 

1.148 

I.I52 

1.124 

1.129 

I-I33 

I.I38 

I.I43 

I.I47 

1.119 

1.124 

I.I28 

I.I33 

1.138 

I.I42 

1.113 

1.118 

I.I23 

I.I27 

1.132 

I.I37 

1.108 

1.113 

1.118 

I.I23 

1.128 

1.132 

1.  102 

1.107 

1.  112 

1.116 

1.  121 

I.I25 

1.097 

I.IO2 

I.IO7 

i.  in 

1.116 

1.  120 

1.092 

1.097 

1.  102 

1.106 

I.  HI 

I.H5 

1.087 

I.O9I 

1.096 

I.IOI 

1.106 

I.  HO 

I.oSl 

1.086 

I.09I 

1.095 

I.IOO 

I.I04 

1.076 

I.OSO 

1.085 

1.090 

1.094 

1.098 

I.O7I 

1.075 

1.  080 

1.084 

"1.089 

1.093 

1.065 

1.069 

1.074 

1.078 

1.083 

1.087 

1.059 

1.064 

1.068 

.072 

1.077 

1.082 

1.053 

1.058 

1.062 

.066 

1.071 

1.076 

1.047 

1.052 

1.056 

.060 

1.065 

I.O7O 

I.04I 

1.046 

1.050 

.054 

1-059 

1.063 

1.035 

1.040 

1.044 

.048 

1.053 

1-057 

I.O29 

1.033 

1.038 

1.042 

1.046 

I.05I 

1.022 

1.027 

1.032 

1.036 

1.040 

1.044 

1.016 

I.02[ 

1.026 

1.030 

1.034 

1.038 

I.OO9 

I.OI4 

1.019 

1.023 

1.027 

I.03I 

1.003 

1.008 

1.  012 

1.017 

I.O2I 

1.025 

ANALYSIS   OF   COMPOUNDS  OF   CARBONS 


(P 

10 


WEIGHT  OF  NITROGEN  IN  ONE  CUBIC  CENTIMETER  OF  THE 
GAS  MEASURED  OVER  WATER— ( Continued) 

748  751  754  757  76o  763  766  769  772 

I.I73       LI77       Ll82  I.l87       LI92       I.I97  1.202       1. 206      1. 211 


I.I76 


11  I.I67  LI72 

12  I.I62  1.167  I.I7I 

J3  I-I57  1.162  1.166 

14  1.152  1.157  1.161 

15  1.147  1.152  1.156 

16  1.141  1.146  1.150 

17  1.136  1.140  1.144 

18  1.130  1.135  1.139 

19  1.125  1.130  1.134 

20  1.  120  I.I25  LI29 

21  I.  114  I.II9  I.I23 

22  I.IOS  I.II3  I.H8 

23  I.I03  I.I07  I-  HI 

24  1.097  i.ioi  1.106 

25  1.092  1.096  i.ioi 

26  1.086  1.090  1.095 

27  1.080  1.084  1.089 

28  1.074  1.078  1.083 

29  i.  068  1.072  1.077 

30  1.062  i.  066  1.971 

31  1.056  i.  060  1.064 

32  1.049  1-053  1-158 

33  1.043  1.047  1.051 

34  1.036  1.040  1.044 

35  1.030  1.034  1.038 


I 

.181 

.186 

.191 

i 

I 

.176 

.181 

.186 

i 

I 

.171 

.176 

.181 

i 

I 

.166 

.171 

•  176 

i 

I 

.161 

.166 

.170 

i 

, 

•155 

1.160 

.164 

, 

I 

.149 

I-I54 

.158 

i 

I 

.144 

1.149 

•!53 

i 

I 

•139 

1.144 

.148 

i 

1 

•134 

1.138 

M43 

x 

I 

.128 

I-I33     ] 

[.138 

i 

I 

.123 

1.127 

[.132 

i 

I 

.116 

1.  121 

[.126 

i 

I 

.in 

1.116 

[.121 

i 

r 

.105 

i.  no 

MIS 

i 

i 

.099 

1.104 

[.108 

i 

r 

•093 

1.098 

[.102 

i 

i 

.087 

1.092 

[.096 

i 

i 

.081 

i.  086 

[.090 

i 

i 

•075 

1.080    ] 

[.084 

i 

i 

.069 

1.073 

[.078 

i 

f 

.062 

1.066 

[.071 

j 

i 

•055 

1.059 

[.064 

i 

i 

.049 

1-053 

[.058 

i 

i 

.043 

1.047 

1.051 

i 

.196  I.2OO  I.2O5 

.190  1.195  I.I99 

I.l85  I.I90  1.194 

I.lSo  I.I85  1.189 

I.I75  I.lSo  I.l84 

69  I.I74  I.I78 

1.163  1.167  I.I72 

I.I58  I.l62  I.l67 

I.I53  LI57  1-162 

1.148  1.152  1.157 

1.142  1.147  1-151 

1.136  1.141  1.145 

131  1.136  1.140 

125  1.130  1.134 

1.119  1.124  1.129 

I.II3  I-II7  1. 122 

1.107  i. in  1.116 

i.ioi  1.105  i. no 

1.095  1.099  LI04 

1.089  L093  1.098 

1.082  1.087  1.092 

1.076  1.080  1.085 

1.069  I'°74  i.°79 

1.063  1.067  1.072 

1.056  i. 060  1.065 


Not  quite  so  accurate  but  still  sufficiently  so  far  all  ordinary 
purposes  is  the  table  giving  the  weight  of  nitrogen  in  one  cubic 
centimeter  of  the  gas  measured  over  water  at  different  tempera- 
tures and  pressures.  The  table  may  also  be  used  for  nitrogen 
measured  over  a  solution  of  potassium  hydroxide  but  for  this 
purpose  there  must  be  added  to  the  observed  barometric  pres- 
sure the  difference  between  the  pressure  of  water  vapor  for  pure 
water  and  for  the  g;ven  solution.  Thus  the  weight  of  the  nitro- 


l8  ORGANIC    CHEMISTRY 

gen  in  one  cubic  centimeter  of  the  gas  measured  over  40  per  cent, 
solution  of  potassium  hydroxide  at  25°  and  751  mm.  barometric 
pressure  is  1.113  mg.  while  if  measured  over  pure  water  it  is 
1.096.  The  error  of  calculation  in  using  this  table  will  not,  in 
most  cases,  exceed  one  part  in  1,000.  The  values  obtained  by 
means  of  some  similar  tables  in  common  use  are  about  one  part 
in  250  too  high,  because  the  tables  are  based  on  the  old,  erroneous 
value  for  the  weight  of  one  cubic  centimeter  of  nitrogen. 

Determination  of  Nitrogen  by  the  Kjeldahl  Method 

Literature — Kjeldahl:  Z.  anal.  Chem.,  22,  366;  Gunning:  Ibid,  28,  188; 
Foerster:  Ibid,  28,  422;  Kober:  J.  Am.  Chem.  Soc.,  30,  1131;  Gill  and 
Grindley:  Ibid,  31*  1249;  Kober:  Ibidf  32,  689. 

The  nitrogen  of  amides,  amines,  proteins  and  of  some  other 
compounds  may  be  determined  by  the  Kjeldahl  method,  which  con- 
sists in  digesting  the  substance  with  hot,  concentrated  sulphuric 
acid,  usually  with  the  addition  of  some  substance  to  aid  in  the 
oxidation,  followed  by  dilution,  neutralization  and  distillation  of 
the  ammonia  from  the  alkaline  solution.  The  nitrogen  of  nitro 
compounds  and  of  nitrates  may  be  determined  by  the  same  meth- 
od, after  previous  reduction. 

Place  in  a  300  cc.,  long  necked,  Kjeldahl  flask,  best  of  Jena 
glass,  0.2  to  0.5  gram  of  the  substance  to  be  analyzed,  add  20  cc. 
of  pure  concentrated  sulphuric  acid,  10  grams  of  potassium  sul- 
phate and  0.5  gram  of  mercury.1  The  mercury  is  best  measured 
in  a  very  small  capillary  tube,  having  a  mark  on  it  to  indicate 
the  quantity  which  should  be  taken.  Support  the  flask  at  an 
angle  of  45°  and  heat  the  contents  over  a  low  flame,  applied 
directly  to  the  glass,  for  one  to  two  hours.  The  contents  of  the 
flask  should  boil  gently  but  not  so  rapidly  that  much  sulphuric 
acid  escapes  from  the  mouth  of  the  flask.  The  operation  must, 
of  course,  be  carried  on  in  a  hood  with  a  good  draft.  If  the 
contents  of  the  flask  does  not  become  colorless  at  the  end  of 
two  hours,  the  oxidation  may  be  finished  by  adding  carefully 
a  small  amount  of  potassium  permanganate. 

1  Some  chemists  use  o.i  gram  of  crystallized  copper  sulphate  instead  of  mercury.  In 
that  case  the  subsequent  use  of  potassium  sulphide  is  not  necessary. 


ANALYSIS   OF   COMPOUNDS  OF   CARBONS  IQ 

Measure  into  a  300  cc.  Erlenmeyer  flask  an  amount  of  N/io 
hydrochloric  acid  about  ten  per  cent,  in  excess  of  that  required 
to  neutralize  the  ammonia  expected  from  the  quantity  of  sub- 
stance taken,  (i  cc.  of  K/io  hydrochloric  acid  is  equivalent  to 
1.4  mg.  N).  Arrange  a  distilling  apparatus  as  shown  in  the 
figure,  the  connection  with  the  Kjeldahl  flask  being  made  by 


Fig.  9. 

means  of  a  Hopkins  distilling  bulb.  The  condenser  tube  is  best 
of  tin  or  aluminum.  The  bulb  tube  connected  to  the  lower  end 
of  the  condenser  should  dip  under  the  surface  of  the  standard 
acid.  When  the  contents  of  the  digestion  flask  is  cooled  suffi- 
ciently, add  150  cc.  of  water  and  cool  again,  then  pour  care- 
fully down  the  side  of  the  flask,  so  that  it  will  run  to  the  bot- 
tom without  mixing,  80  cc.  of  a  solution  containing  30  grams 
of  sodium  hydroxide  and  2  grams  of  potassium  sulphide.  Add 
two  or  three  pieces  of  granulated  zinc.  Connect  at  once  with 


20  ORGANIC   CHEMISTRY 

the  distilling  tube,  mix  the  contents  of  the  flask  by  careful  shak- 
ing and  distil  over  125-150  cc.  Titrate  the  excess  of  acid  with 
standard  alkali,  using  methyl  orange  or  congo  red  or  methyl  red 
as  indicator. 

A  blank  experiment  should  be  carried  out  with  the  same 
quantities  of  all  the  reagents,  except  that  only  i  to  2  cc.  of 
the  standard  acid  should  be  used.  Any  nitrogen  found  in  the 
blank  determination  is  to  be  subtracted  from  the  amount  found 
in  the  analysis. 

Instead  of  distilling  the  ammonia  as  described  it  may  be 
aspirated  over  into  the  standard  acid  by  Kober's  method. 

Determination  of  Halogens,  Sulphur  or  Phosphorus  by 
Carius's  Method 

Literature — C'arius  :  Ber.,  3,  697 ;  Kiister :  Ann.,  285,  340 ;  Walker  and 
Henderson:  Chem,  News,  71*  103. 

Prepare  a  tube  of  glass  designed  for  sealing  tubes  (the 
"Einschmelzrohren"  of  Schott  and  Genossen  are  excellent)  hav- 
ing an  inner  diameter  of  14-16  mm.  walls  2  mm.  thick  and  a 
length  of  35-40  cm.  Seal  very  carefully  at  one  end,  taking 
care  that  the  walls  fall  together  somewhat  during  the  sealing 
and  that  no  portion  becomes  thin.  Introduce  one-half  a  gram 
of  silver  nitrate  and  1-1.5  cc-  °f  Pure  nitric  acid  of  sp.  gr.  1.50 
(not  the  red  fuming  acid).  The  amount  of  acid  should  be  20 
per  cent,  in  excess  of  that  required  for  the  complete  oxidation 
of  the  substance  on  the  supposition  that  it  is  reduced  to  nitrous 
acid.  A  larger  amount  of  acid  is  not  necessary  and  increases 
the  danger  of  explosion.  Introduce  the  substance,  weighed  in 
a  small  tube,  2-3  cm.  long  and  6-8  mm.  in  diameter.  Seal  the 
other  end  of  the  tube  carefully,  drawing  it  out  very  slowly  to 
prevent  the  wall  from  becoming  thin  at  any  point  and  having 
at  the  end  a  capillary  tip  4-6  cm.  long  and  with "  an  internal 
diameter  near  the  end  of  ^  mm.  or  less.  Place  the  tube  in 
a  bomb  furnace,  rais'e  the  temperature  slowly  to  320°  and  keep 
it  at  3io°-33O°  for  two  hours.  It  need  hardly  be  said  that  the 
furnace  must  be  so  placed  with  the  ends  protected  by  iron  or 
heavy  wooden  shields  that  no  one  can  be  injured  in  case  of  an 


ANALYSIS   OF   COMPOUNDS   OF   CARBONS 

explosion.  Where  the  furnace  is  thoroughly  cold,  remove  the 
tube  very  carefully  always  keeping  several  thicknesses  of  a 
towel  or  heavy  cloth  between  the  tube  and  the  'hand  or  body 
and  wrapping  it  well  in  a  towel  as  soon  as  it  is  removed  from 
the  furnace.  A  better  method,  which  should  always  be  used 
when  possible,  is -to  have  a  furnace  with  movable  iron  tubes  and 
to  keep  the  sealed  tube  almost  entirely  in  the  iron  tube  until 
the  pressure  has  been  relieved  by  holding  the  tip  in  the  flame 
of  a  burner  till  the  internal  pressure  has  blown  out  an  opening. 
During  this  operation  the  tube  is  held  with  the  end  bearing 
the  capillary  tip  high  enough  so  that  the  contents  of  the  tube 
will  run  to  the  lower  end.  The  eyes  should  be  protected  by 
goggles.  After  the  pressure  has  been  relieved  the  end  of  the 
tube  is  cut  off  and  the  silver  halide  is  carefully  rinsed  out  into 
a  small  beaker.  If  some  of  the  silver  halide  can  not  be  removed 
from  the  tube  by  rinsing,  it  may  be  dissolved  in  a  very  little  am- 
monia and  the  solution  added  to  the  contents  of  the  beaker.  In 
such  a  case  the  solution  in  the  beaker  must  stand  in  the  dark 
till  the  precipitate  has  settled  before  filtering.  In  the  case  of 
silver  iodide  or  bromide  it  is  advisable  to  digest  the  solution 
and  precipitate  on  the  water-bath  for  a  short  time  to  decom- 
pose double  compounds  which  are 'formed  with  the  excess  of  sil- 
ver nitrate.  The  solution  is  filtered  on  a  Gooch  crucible,  the 
precipitate  washed  and  finally  dried  at  I5O°-2OO°. 

For  the  determination  of  sulphur  or  phosphorus  the  addition 
of  silver  nitrate  is  omitted  and  the  sulphuric  or  phosphoric  acid 
in  the  diluted  oxidation  mixture  is  determined  by  the  usual 
analytical  methods  with  use  of  barium  chloride  or  molybdic  mix- 
ture. 

Determination  of  Halogens  or  Sulphur  by  Pringsheim's  Method 

Literature.— Pringsheim :  Am.  Chem.  J.,  31,  386;  Ber.,  36,  4244; 
Schreiber:  J.  Am.  Chem.  Soc.,  32»  977- 

About  0.2  gram  of  the  substance  is  mixed  with  sodium  per- 
oxide in  a  brass  or  steel  crucible  of  the  form  shown  in  Fig.  10. 
If  the  substance  contains  75  per  cent,  of  carbon  and  hydrogen. 


22 


ORGANIC   CHEMISTRY 


18  times  its  weight  of  the  peroxide  should  be  used.  If  it  contains 
50  to  75  per  cent,  of  carbon  and  hydrogen,  16  times  its  weight 
should  be  used;  if  it  contains  25  to  50  per  cent,  it  should  be 
mixed  with,  half  of  its  weight  of  sugar  and  if  it  contains  less 
than  25  per  cent,  it  should  be  mixed  with  an  equal  weight  of 
sugar,  the  amount  of  peroxide  being  in  the  former  case  16  times 
and  in  the  latter  caseviS  times  the  weight  of  the  mixture.  For 
practically  all  cases  a  stock  mixture  of  one  part  of  sugar  with 
25  parts  of  sodium  peroxide  may  be  prepared  and  one  part 
of  the  substance  to  be  burned  mixed  with  30-32  parts  of  this 


Fig.  10. 

mixture.  The  sugar  and  substance  must  be  finely  powdered,  the 
latter,  of  course,  before  weighing.  They  are  intimately  mixed  with 
the  sodium  peroxide  in  the  crucible  by  means  of  a  small  nail,  which 
is  left  in  the  crucible  during  the  ignition.  The  cover  is  placed  on 
the  crucible  and  the  latter  is  immersed  in  distilled  water  in  a  porce- 
lain dish  to  within  3  or  4  mm."  of  its  upper  edge.  The  mix- 
ture is  ignited  by  thrusting  a  red  hot  iron  wire  through  the  hole 
in  the  lid.  If  the  mixture  ignites  very  rapidly  with  the  evolu- 
tion of  considerable  gas,  and  smoke  and  flame  appear  through 
the  nail  hole  in  the  lid,  too  much  carbonaceous  matter  has  been 
used.  If  the  mixture  fails  to  ignite  throughout,  too  much  so- 
dium peroxide  has  been  taken.  In  either  case  it  is  best  to  repeat 


ANALYSIS   OF   COMPOUNDS  OF   CARBONS  23 

the  ignition,  though,  if  the  sample  is  valuable  it  can  be  saved 
in  the  second  case  by  completing  the  ignition  over  the  blast. 
When  the  reaction  is  complete,  the  crucible  is  turned  on  its  side 
and  the  contents  of  the  dish  warmed  gently  till  solution  is  com- 
plete. The  solution  is  then  filtered,  5  cc.  of  a  strong  solution  of 
sodium  sulphite  added  to  reduce  any  oxygen  acids  of  the  halogens 
which  may  have  been  formed,  and  then  dilute  sulphuric  acid  to 
strongly  acid  reaction.  The  halogen  acid  may  be  precipitated 
in  the  usual  manner  with  silver  nitrate  or  it  may  be  titrated  by 
Volhard's  method.  In  the  latter  case  an  excess  of  silver  nitrate 
should  be  added  either  before  or  immediately  after  acidifying  and 
the  solution  boiled  to  expel  sulphur  dioxide  before  titrating 
back  with  the  thiocyanate.  Also,  if  chlorine  is  to  be  determined, 
the  silver  chloride  must  be  filtered  off  before  titrating  (RosanofF 
and  Hill:  J.  Am.  Chem.  Soc.,  29,  269).  Sulphur  and  phosphorus 
may  also  be  determined  by  burning  the  substance  with  sodium 
peroxide  followed  by  precipitation  from  the  acidified  solution. 
The  method  is  not  adapted  for  use  with  liquids. 

Determination  of  Halogens  by  Reduction  with  Sodium  and 
Absolute  Alcohol 

Literature.— Stepanow :  Ber.,  39,  4056;  Bacon:  J.  Am.  Chem.  Soc.,  3', 
49- 

For  liquid  substances  and  substances  which  ignite  on.  mixing- 
with  sodium  peroxide  the  method  of  Stepanow  is  very  suitable.  In- 
troduce into  150  cc.  Kjeldahl  flask  0.2  gram  of  the  substance  to  be 
analyzed  and  35  cc.  of  absolute  alcohol  (98  per  cent,  at  least)  if 
it  contains  chlorine,  18  cc.  if  it  contains  bromine  or  13  cc.  if  it 
contains  iodine.  Connect  the  flask  with  an  upright  condenser, 
support  it  on  a  thin  sheet  of  asbestos  on  a  wire  gauze,  warm 
gently  till  the  substance  is  dissolved  and.  add  gradually,  during 
at  least  30  minutes,  through  the  condenser,  3.5,  IJT,  or  i.i  grams 
of  sodium  according  as  the  substance  contains  chlorine,  bromine 
or  iodine.  Toward  the  end  keep  the  solution  boiling  gently  with 
a  burner  and  boil  the  solution  for  one  hour  after  the  sodium 
is  all  dissolved.  Allow  the  solution  to  cool  to  50°  or  60°,  add, 
cautiously,  50  cc.  of  water  through  the  condenser,  cool,  acidify 


24  ORGANIC   CHEMISTRY 

with  nitric  acid,  add  an  excess  of  standard  silver  nitrate,  filter, 
if  the  halide  is  chlorine  (Rosanoff  and  Hill:  J.  Am.  Chem.  Soc., 
29,  269),  add  ferric  sulphate  and  titrate  with  a  standard  solution 
of  ammonium  thiocyanate  by  Volhard's  method. 

Determination  of  Barium,  Strontium,  or  Calcium  in  Salts  of  Or- 
ganic Acids. — Weigh  0.2  to  0.3  gram  of  the  salt  in  a  platinum 
crucible  and  heat  in  an  air-bath  for  I  to  2  hours  at  100°  to  200° 
according  to  the  nature  of  the  salt.  In  the  case  of  salts  of  un- 
known properties,  it  is  safest  to  dry  to  constant  weight  in  a  vac- 
uum desiccator  first,  then  successively  at  100°,  135°,  -175°  afld 
200°,  noting  at  which  temperature  a  constant  weight  can  be  ob- 
tained without  decomposition.  After  determining,  as  above, 
water  of  hydration,  if  present,  add  to  the  salt  one  or  two 
drops  of  concentrated  sulphuric  acid  and  heat  very  gently  over  a 
low  flame  till  fumes  of  sulphuric  acid  cease  to  escape,  then  at 
faint  redness  till  the  sulphate  formed  is  pure  white.  Cool  and 
weigh,  then  moisten  with  a  drop  of  concentrated  sulphuric  acid 
and  heat  very  gently  till  the  acid  is  expelled  and  finally  again  to 
faint  redness.  If  the  contents  of  the  crucible  increases  in  weight, 
the  presence  of  a  little  sulphide  at  the  end  of  the  first  heating 
is  indicated  and  the  second  weight  is  to  be  taken.  In  calcium 
salts  the  metal  may  be  determined  as  calcium  oxide  by  direct 
ignition  over  the  blast  lamp. 

Determination  of  Sodium,  Potassium  or  Other  Metals. — Sodium 
and  potassium  may  be  determined  as  sulphates  by  ignition  with 
sulphuric  acid  as  described  above  but  the  temperature  of  the 
crucible  must  never  be  above  dull  redness  for  fear  of  volatiliz- 
ing some  of  the  salt.  Also,  after  the  salt  is  pure  white,  some 
solid  ammonium  carbonate  should  be  thrown  into  the  crucible 
several  times  and  the  heating  continued  to  convert  any  acid  sul- 
phate present  into  the  neutral  salt. 

In  silver  salts  the  silver  may  be  determined  as  metallic  silver 
by  gentle  ignition  in  a  porcelain  crucible. 


Chapter  II 

GENERAL  OPERATIONS 

The  most  important  general  operations  used  in  the  prepara- 
tion of  pure  substances  are  separation  by  means  of  solvents,  ex- 
traction witn  ether  or  other  immiscible  solvents  (p.  167,  54),  crys- 
tallization (p.  129),  fractional  crystallization  (p.  122),  fractional 
distillation,  distillation  under  diminished  pressure  (p.  172),  dis- 
tillation with  steam  (p.  71),  sublimation  (p.  80),  filtration 
(p.  120),  and  determination  of  the  melting-point,  boiling-poirjt 
and  specific  gravity.  In  this  chapter  only  fractional  distillation, 
the  determination  of  the  boiling-point,  the  determination  of  the 
melting-point  and  the  determination  of  specific  gravity  will  be 
considered.  The  other  operations  will  be  discussed  in  connec- 
tion with  preparations  in  which  they  are  used. 

At  the  close  of  the  chapter  directions  for  the  distillation  of 
wood  and  separation  of  the  various  products  formed  are  given 
as  an  illustration  of  a  number  of  operations  common  both  in  the 
laboratory  and  in  technical  processes. 

1.  Fractional  Distillation  and  the  Determination  of  Boiling- 
points. — Carbon  tetrachloride  and  aniline. 

Literature — Theory  of  fractional  distillation;  Nernst:  Theoretische 
Chemie,  6th  Edition,  p.  in;  Noyes :  Organic  Chemistry,  p.  13;  Correction 
of  thermometers;  Crafts:  Am.  Chem.  J.,  5»  324;  Circular  of  the  Bureau 
of  Standards  Washington ;  Rimbach :  Ber.,  22,  3072 ;  Apparatus  for  frac- 
tional condensation;  Hahn :  Ber.,  43»  419;  C.  A.,  IQ™,  1168;  Prevention 
of  bumping,  Scudder:  J.  Am.  Chem.  Soc.,  25,  163;  H.  Meyer:  Analyse 
und  Konstitutionsermittelung  org.  Verbindungen,  2,  Auf  1.  pp.  46-47 ; 
Determination  of  boiling-point  of  a  small  amount  of  substance;  Mulli- 
ken:  A  Method  for  the  Identification  of  Pure  Organic  Substances,  p. 
222;  Alex.  Smith  and  Menzies :  J.  Am.  Chem.  Soc.,  32,  897;  See  also  p 
269. 

25   grams  aniline. 

25  grams  carbon  tetrachloride. 

Place  25  grams  of  carbon  tetraohloride  in  a  50  cc.  flask  con- 


26  ORGANIC   CHEMISTRY 

taining  5  grams  of  powdered  calcium  chloride.  In  a  second 
flask  of  the  same  size  place  25  grams  of  aniline  with  5  grams 
of  powdered  potassium  hydroxide.  After  an  hour,  or  better 
after  standing  over  night,  filter  one  of  the  liquids  through  a  dry 
filter  into  a  50  cc.  distilling  bulb  and  distil  slowly  with  the  ap- 
paratus shown  in  the  figure.  The  thermometer  is  held  in  place 
by  a  tightly  fitting,  sound  and  carefully  bored  cork,  not  a  rub- 
ber stopper.  It  is  usually  best  to  make  the  hole  with  a  cork-borer 
a  little  smaller  than  the  thermometer  and  enlarge  it  by  means  of  a 
round  file.  The  bulb  of  the  thermometer  must  always  be  placed 
a  little  below  the  side  tube  of  the  distilling  bulb  but  should  never 


Fig.  ii. 

be  placed  within  the  liquid  or  too  close  to  it.  The  condensing 
tube  for  the  present  case  may  be  about  I  cm.  in  internal  diameter 
and  60  cm.  long.  For  more  volatile  liquids  than  carbon  tetra-\ 
chloride  or  for  the  rapid  distillation  of  larger  amounts  of  sub- 
stance a  Liebig's  condenser  should  be  used.  The  condensing 
tube  may  be  drawn  out  at  the  upper  end  so  that  the  side  tube  of 
the  distilling  bulb  will  just  enter  it  and  connected  with  the  latter 
by  slipping  a  tightly  fitting  rubber  tube  over  both.  The  distill- 
ing bulb  is  to  be  heated  over  a  low  flame  applied  directly  to 
the  bulb.  A  micro  burner,  if  available,  is  most  satisfactory  for 
the  purpose  when  a  small  quantity  of  liquid  is  to  be  distilled. 
Collect  the  first  portion  of  the  distillate  in  a  dry  test  tube  till  the 
thermometer  indicates  a  temperature  within  i°  of  the  boiling- 


GENERAL  OPERATIONS  27 

point  (76.7°  for  carbon  tetrachloride,  183.7°  for  aniline),  then 
collect  the  principal  portion,  which  should  boil  within  an  in- 
terval of  two  degrees,  in  a  small  dry,  weighed  flask. 

A  small  additional  amount,  boiling  within  the  proper  interval 
may  usually  be  obtained  by  redistilling  the  portions  collected 
below  and  above  the  interval  chosen. 

Having  determined  the  weights1  of  carbon  tetrachloride  and 
aniline  obtained,  mix  them  together  and  subject  the  mixture  to 
fractional  distillation  collecting  the  successive  fractions  in  a  se- 
ries of  dry  flasks  or,  for  the  smaller  fractions,  of  test-tubes, 
labelling  each  with  a  gummed  label  marked  with  a  pencil,  or 
with  a  pencil  which  will  write  on  glass.  Eight  or  ten  fractions 
should  be  collected,  the  temperature  intervals  being  chosen  with 
reference  to  the  amounts  of  the  distillates  at  different  tempera- 
tures. The  use  of  good  common  sense  as  to  the  amount  which 
should  be  collected  in  each  fraction  and  the  corresponding  tem- 
perature intervals  to  be  chosen  is  one  of  the  most  important  points 
in  fractional  distillation.  In  general,  the  fractions  should  be 
larger,  and  the  temperature  intervals  also  shorter,  at  points  near 
the  boiling-points  of  the  substances  to  be  separated. 

When  the  whole  has  been  distilled  the  apparatus  is  carefully 
cleaned  and  dried  and  the  lowest  boiling  fraction  returned  to  the 
bulb.  This  is  then  distilled  and  the  first  distillate  collected 
in  the  same  flask  but  for  a  much  narrower  interval  of  tempera- 
ture than  before,  a  second  portion  being  collected  in  a  new 
receptacle.  When  the  lower  temperature  for  the  second  fraction 
from  the  first  distillation  is  approached  that  is  added  to  the 
bulb  through  a  small,  dry,  funnel,  and  the  distillation  continued, 
the  distillate  being  collected,  of  course,  in  the  proper  flask  or  tube 
corresponding  to  the  boiling-point.  While  the  intervals  of  tem- 
perature in  the  neighborhood  of  the  boiling-points  of  carbon 
tetrachloride  and  of  the  aniline  should  be  shorter  on  the  second 
distillation  the  intervals  between  may  be  lengthened,  so  that  the 
total  number  of  fractions  is  not  increased.  If  a  considerable 
portion  is  obtained  boiling  within  an  interval  of  two  degrees  of 
the  boiling-points  of  carbon  tetrachloride  and  aniline  respectively, 

1  Weigh  roughly  within  o.i  to  0.2  gram. 


28  ORGANIC   CHEMISTRY 

those  fractions  need  not  be  distilled  again  but  the  intermediate 
fractions  may  be  distilled  once  more  to  increase  the  amounts 
of  these  two  principal  fractions.  Weigh  these  two  fractions  and 
determine  the  percentage  yield. 

The  slow  distillation,  which  the  air  conjdenser  makes  necessary 
to  avoid  loss  of  carbon  tetrachloride,  conduces  to  a  better  separa- 
tion, and,  in  general,  distillation  should  not  be  conducted  too 
rapidly  in  fractioning.  A  general  rule  is  that  the  liquid  should 
drop  from  the  end  of  the  condenser  at  the  rate  of  two  drops 
a  second.  The  neck  of  the  flask  should  always  be  placed  over 
the  end  of  the  condensing  tube  to  prevent  loss  by  evaporation. 
With  volatile  or  hygroscopic  liquids  the  space  between  the  con- 
densing tube  and  the  neck  of  the  flask  should  be  closed  with  cot- 
ton or  with  a  cork  having  a  V  shaped  piece  cut  from  its  side  to 
allow  escape  of  air. 

When  substances  differing  but  little  in  their  boiling-points  are 
to  be  separated  a  Laenburg  distilling  bulb  (p.  172)  a  Hempel  tube 
filled  with  glass  beads  (p.  36)  or  a  Hahn  fractioning  head  (loc. 
cit.)  may  be  used  to  advantage. 

If  the  thread  of  the  thermometer  is  not  entirely  immersed  in 
the  vapor,  a  correction  must  be  added  to  its  reading.  This  may 
be  taken  from  Rimbach's  table  or  calculated  by  the  formula: 

Cor.  =  +  N(*  —  00.000154. 

N  =  Number  of  degrees  on  the  stem  of  the  thermometer 
below  the  temperature  read. 

t  =  temperature  read. 

tf  =  Average  temperature  of  the  stem. 

0.000154  —  Coefficient  of  apparent  expansion  of  mercury  in 
glass. 

The  thermometer  must  also  be  tested  to  determine  if  it  reg- 
isters correctly.  This  is  best  done  by  means  of  the  boiling- 
point  of  some  pure  substance  which  boils  near  the  boiling-point 
to  be  determined.  Suitable  substances  for  this  purpose  are: 

Ethyl  ether 34.6° 

Water 100    ° 

Ethvlene  bromide 130.3° 

Aniline   183.7° 

Naphthalene 218.1° 

Benzophenone *. 306.1° 


GENERAL  OPERATIONS  29 

For  the  last  two  the  boiling-points  under  varying  pressures 
have  been  accurately  determined.  Crafts :  Am.  Chem.  J.,  5,  324. 

In  case  the  pressure  of  the  air  is  greater  or  less  than  760  mm. 
a  correction  must  be  applied.  For  liquids  which  do  not  as- 
sociate, when  the  pressure  is  not  far  from  760  mm.  the  cor- 
rection for  a  difference  of  10  mm.  in  the  pressure  may  be  found 
by  dividing  the  absolute  temperature  of  the  boiling-point  by 
850.  For  associative  liquids,  as  alcohols,  acids  and  hydroxyl 
compounds  generally,  the  factor  is  1020.  (Alex.  Smith  and 
Menzies:  J.  Am.  Ch.  Soc.,  32,  907.)  The  following  table  cal- 
culated on  this  basis  will  be  found  convenient. 

Boiling-point  ^-Correction  for  a  difference  of  lomm.  in  the  pressure — . 

(Ordinary  scale)  For  non-associating  liquids  For  alcohols,  acids,  etc. 

50°                                                           0.38°  0.32° 

100°                                                0.44°  0.37° 

150°                                                           0.50°  0.42° 

200°                                                                 0.56°  0.46° 

250°                                                                 0.62°  0.5I0 

300°  0.68°  0.56° 

350°  0.74°  0.6 1  ° 

400°  0.80°  0.66° 

By  using  a  set  of  Anschiitz  thermometers,  each  of  which 
has  a  range  of  only  60°  to  70°,  the  correction  for  the  stem  may 
be  made  very  small  and  usually  may  be  neglected. 

2.  Determination  of  Melting-points. — Urea,  phthalic  anhydride, 
/-toluidine. 

Literature.— Apparatus,  Scudder:  J.  Am.  Chem.  Soc.,  25,  161 ;  Thiele: 
Ber.,  40,  996;  Correction  for  thermometers,  Crafts:  Amer.  Chem.  J.,  5> 
324;  Rimback:  Ber.,  22,  3072. 

The  purity  of  solid  substances  is,  in  many  cases,  most  easily 
tested  by  means  of  the  melting-point.  For  this  purpose  the 
substance  must  be  perfectly  dry.  The  drying  can  be  effected 
by  allowing  the  body  to  lie  for  a  sufficient  length  of  time  on 
filter-paper,  or  on  clean,  porous  porcelain,  best  over  sulphuric 
acid  in  vacua. 

A  lot  of  capillary  tubes  for  the  determination  of  melting- 
points  may  be  prepared  by  taking  a  soft  glass  tube  with  not 
too  thin  walls,  4  to  5  mm.  in  external  diameter,  and  drawing 


3O  ORGANIC   CHEMISTRY 

it  out  as  indicated  above.     (See  Fig.    12.)     The  tube  is  then 


Fig.  12. 

sealed  off  near  each  bulb,  and  the  closed  tubes  kept  till  needed. 
For  use,  the  bulb  is  cut  in  two  by  scratching  with  a  file  and 
breaking.1  The  finely  powdered  substance  is  put  into  the 
wide  end  of  the  tube  and  shaken  down,  or  pushed  down 
to  the  point  with  a  clean  platinum  wire.  For  a  melting- 
point  bath  the  best  for  general  use  is  a  round-bottomed,  75  cc. 
flask,  with  a  rather  long  neck.  In  the  mouth  is  placed  a  stopper, 
perforated  so  that  the  thermometer  will  pass  easily  through  it, 
and  be  held  in  place  by  a  small  wooden  wedge,  e.g.,  a 
match  stick.  Through  the  side  of  the  cork  passes  a 
small  platinum  wire  with  loops,  as  indicated  in  the  figure. 
(See  Fig.  13).  If  moistened  with  the  sulphuric  acid, 
the  tube  will  adhere  to  the  thermometer  by  capillary 
attraction,  but  such  an  arrangement  is  less  secure.  Ihe 
part  of  the  capillary  tube  containing  the  substance  should 
lie  in  contact  with  the  bulb  of  the  thermometer.  The 
bath  may  be  heated  rapidly  with  a  free  flame  till  the 
temperature  approaches  the  melting-point,  and  then  very 
slowly.  In  case  of  bodies  which  decompose  at  or  near 
their  melting-points,  the  thermometer  and  the  tube  should 
be  brought  as  quickly  as  possible,  without  danger  of 
Fig.  13.  breaking  the  thermometer,  into  the  hot  bath  and  the 
latter  brought  quickly  to  the  melting-point.  The  result,  in  such 
cases,  cannot  be  very  accurate. 

When,  as  is  usually  the  case,  the  stem  of  the  thermometer  is 
not  immersed  in  the  sulphuric  acid  to  the  point  to  which  the 
mercury  rises,  a  correction  similar  to  that  for  boiling-points 
must  be  applied.  (See  p.  28.) 

In  general,  a  sharp  melting-point,  within  an  interval  of  one 
degree,  at  most,  is  characteristic  of  a  pure  substance,  while  im- 
pure substances  melt  indefinitely. 

1  Some  chemists  prefer  thin,  straight  capillary  tubes  prepared  by  drawing  out  a  test- 
tube.  The  tube  should  be  about  the  size  of  the  lead  of  a  lead  pencil. 


GENERAL  OPERATIONS  3! 

Instead  of  the  bulb,  shown  in  Fig.  14,  the  Thiele  apparatus 


Fig.  14. 

shown  in  Fig.  15  may  be  used  to  advantage.  For  temperatures  be- 


Fig.  15. 

low  300°  concentrated  sulphuric  acid  may  be  used  in  the  bulb  or 
apparatus  but  a  mixture  of  7  parts  of  acid  with  3  parts  of  po- 
tassium sulphate  gives  off  less  of  acid  vapors  and  may  be  heated 
to  a  higher  temperature  without  boiling.  A  mixture  of  6  parts 
of  acid  with  4  parts  of  potassium  sulphate  may  be  used  to  a 
temperature  of  365°  but  becomes  pasty  or  solid  at  ordinary 
temperatures.  For  still  higher  temperatures  zinc  chforide  may 


32  ORGANIC   CHEMISTRY 

be  used  but  this  must  be  poured  into  a  shallow  dish  to  solidify, 
as  it  expands  on  crystallizing  and  would  burst  the  bulb.  If 
the  sulphuric  acid  darkens  after  using  for  some  time,  it  may  be 
cleared  by  adding  a  fragment  of  potassium  nitrate. 

3.  Determination  of  Specific  Gravity. — Specific  gravity  of 
alcohol. 

Literature — Circular  No.  9,  Bureau  of  Standards,  Washington,  Test- 
ing of  Glass  Volumetric  Apparatus;  Circular  No.  16,  Testing  of  Hy- 
drometers; Circular  No.  19,  Standard  Density  and  Volumetric  Tables; 
Traube:  Physikalisch-Chemische  Methoden,  pp.  12-24;  Ostwald-Luther : 
Hand  und  Hilfsbuch  zur  ausfiihrung  Physiko-Chemischer  Messungen, 
2nd  Edition,  pp.  141 ;  Morley :  Alcoholometric  Table,  J..  Am.  Chem.  Soc . 
26,  1185;  A  new,  more  accurate  table  will  soon  be  issued  by  the  Bureau 
of  Standards. 

Prepare  a  small  bulb  by  drawing  out  a  tube  with  a  diameter  of 
I  cm.  and  wall  about  I  mm.  thick  to  the  form  shown  in  the 
Fig.  1 6.  It  should  be  drawn  out  in  such  a  manner  that  the 

\         / 


A  V 

B 

Fig.  16. 

tube  does  not  become  too  thin  at  A  and  that  the  internal  diameter 
at  that  point  is  about  2  mm.  Then  seal  the  tube  at  B  and  form 
a.  flattened  end  leaving  a  capacity  of  about  I  cc.  Anneal  the 
bulb  carefully  in  the  flame,  cool,  cut  the  tube  off  about  ^  cm. 
above  the  narrowest  point,  round  the  cut  edge  in  the  flame  and 
make  a  narrow  mark  at  A,  using  a  moistened  file,  .best  moistened 
with  a  solution  of  camphor  in  turpentine.  (A  file  moistened 
with  this  mixture  will  cut  or  bore  glass  rapidly.)  Clean  the 
bulb  carefully  with  alcohol,  introducing  it  and  removing  it  with 
a  tube  drawn  out  to  a  capillary  of  such  size  that  it  will  pass 
through  the  neck  of  the  bulb.  Warm  the  bulb  gently  and  dry 
it  by  drawing  air  through  it  with  the  same  capillary  tube.  Cool 
for  half  an  hour  in  the  balance  case  and  weigh  accurately.  Fill 
the  bulb  with  water  to  a  point  just  above  the  mark,  using 
the  same  tube  as  before.  Bring  the  water  in  a  500  cc.  beaker 


OPERATIONS  33 

exactly  to  20°.  Place  the  bulb  in. the  water,  supporting  it  with 
a  shelf  so  placed  that  the  water  comes  to  a  point  just  below  the 
neck  of  the  bulb.  After  ten  minutes  bring  the  liquid  in  the 
bulb  exactly  to  the  mark  by  drawing  out  the  excess  with  the 
capillary  pipette.  Wipe  the  bulb  dry  and  weigh  after  half  an 
hour.  The  weight  of  the  water  multiplied  by  1.00282  will  give 
the  volume  of  the  bulb  in  cubic  centimeters.1  The  volume  at 
15°  will  be,  for  a  capacity  of  I  cc.,  0.00012  cc.  less  and  at  25° 
0.00012  cc.  more  than  at  20°,  owing  to  the  contraction,  or 
expansion  of  the  glass.  Remove  the  water,  fill  the  bulb  with 
alcohol,  remove  this  and  repeat  twice,  then  dry  as  before.  Fill 
the  bulb  with  alcohol,  set  it  in  the  beaker  of  water,  and  repeat 
the  operations  exactly  as  before.  To  the  apparent  weight  of  the 
alcohol  there  must  be  added  0.00109  gram  for  each  cubic  centi- 
meter in  the  capacity  of  the  bulb,  to  correct  for  the  buoyancy  of 
the  air.  The  specific  gravity  referred  to  water  at  4°  will,  of 
course,  be  the  corrected  weight  of  the  alcohol  divided  by  the 
volume,  in  cc.,  of  the  bulb. 

It  is  always  desirable  to  know  the  specific  gravity  of  a  new 
substance  at  two  different  temperatures.  For  this  purpose  the 
capacity  of  the  bulb  may  be  calculated  at  15°  and  at  25°  by  the 
rule  given  above.  The  bulb  may  be  filled  with  alcohol  at  15°  or 
25°  by  keeping  the  water  in  the  beaker  at  the  desired  tempera- 
ture. To  the  apparent  weight  must  be  added  o.ooin  gram  at 
15°  or  0.00107  gram  at  25°  for  each  cc.  as  the  correction  to  a 
vacuum. 

Unless  it  is  desired  to  determine  the  specific  gravity  to  the 
fifth  decimal,  the  value  o.oon  may  be  used  for  the  corrrection  at 
pressures  above  750  mm.  or  o.ooio  at  pressures  of  700  to  750 
mm. 

A  higher  degree  of  accuracy  may  be  obtained  by  the  use  of 
a  larger  pyknometer  but  this  is  useless  unless  the  liquid  examined 
is  of  a  very  high  degree  of  purity.  Determine  the  strength  of 
the  alcohol  by  weight  and  by  volume  with  the  use  of  Mor- 
ley's  table,  (loc.  cit.) 

1  One  gram  of  water  at  20°  fills  a  volume  of  T.  001768  cc.  and  one  gram  of  water  as  indi- 
cated by  brass  weights  is  really  1.001053  gram,  when  corrected  for  the  buoyancy  of  the  air. 

3 


34 


ORGANIC    CHEMISTRY 


4.  Distillation  of  Wood. 

Literature — J.  Anal  and  Appl.  Chem.,  5>  241 ;  Met.  and  Chem.  Eng.,  8, 
I55»  433-     F°r  acetone  see  also  33i  p.  92. 

1,200  grams  of  wood. 

Put    1,200   grams   of    wood,    cut   into   billets    about    an   inch 
square  into  the  iron  retort  shown  in  Fig.   17.     The  retort  is  of 


Fig.  17. 

.. 

cast  iron,  15  cm.  inside  diameter  and  20  cm.  deep,  with  walls 
12  mm.  thick.  It  is  fitted  with  a  thermometer,  reaching  well 
down  into  the  charge  of  wood  and  with  a  glass  delivery  tube. 
Both  the  thermometer  and  delivery  tube  should  pass  through 
carefully  bored,  tightly  fitting  cork  stoppers.  The  cover  of  the 
retort  is  held  on  with  iron  dogs  and  wedges,  a  thin  sheet  of  as- 
bestos being  interposed  between  the  cover  and  the  body  of  the 
retort  to  insure  a  tight  joint.1  The  retort  is  supported  by  a 
piece  of  thick  asbestos  board  bent  to  the  proper  shape  and  held 
in  place  with  wire.  Openings  are  cut  in  the  board  above  and 
below  for  the  entry  and  exit  of  air  and  the  retort  is  heated  by 
a  good  triple  burner. 

1  Instead  of  the  retort  described,  the  one  shown  in  Fig.  17  A  may  be  used.  This  is  60  cm. 
long  and  7.5  cm.  in  diameter,  with  walls  about  6  mm.  thick.  There  is  a  2.5  cm.  flange  at 
the  end  ground  smooth  and  fitted  with  a  perforated  iron  plate  attached  as  described 
above.  The  massive  cast  iron  retort  has  proved  more  satisfactory. 


GENERAL  OPERATIONS  35 

Connect  the  delivery  tube  from  the  retort  with  a  750  cc.  Er- 


s+ 


1=1 


n 


ftll 


-LJL 


Fig.  I7A.— Single  tube  retort,  heated  by  gas,  for  the  distillation  of  wood  or  calcium 
acetate.    The  whole  apparatus  is  enclosed  in  a  case  of  asbestos  board  to  con- 
serve the  heat.    The  cover  with  the  asbestos  washer  (A)  is  held  in  place 
by  two  dogs  and  wedges  (D).     The  volatile  products  pass  out  from 
the  retort  through  tube  (T)  to  the  condenser. 


lenmeyer  flask  and  the  latter  with  a  condenser  and  settling  bottle 
(2l/2   liters)   as  shown  in  Fig.   18.     The  exit   from  the  settling 


CLn   apparatus    for  collecting  J}&s  t ilia  1 6  from 
Fig.  18. 


bottle  is  connected  with  a  burner  where  the  combustible  gases 
are  burned  as  they  escape.     When  all  is  ready  heat  the  retort 


30  ORGANIC   CHEMISTRY 

moderately  so  that  toward  the  end  of  the  distillation  the  ther- 
mometer goes  to  2io°-22O°.  Under  these  conditions  the  dis- 
tillation will  require  about  5  hours  and  the  products  will  be 
about  40  per  cent  charcoal,  40  per  cent,  distillate,  and  20  per 
cent.  gas.  If  the  heating  is  more  rapid,  so  that  the  distillation 
is  completed  in  three  hours  and  the  temperature  reaches  300°, 
the  charcoal  will  be  only  about  30  per  cent.,  the  distillate  45 
per  cent,  and  the  gas  25  per  cent.  In  the  latter  case  the  amount 
of  tar  will  also  be  increased  and  the  products  obtained  are  likely 
to  be  more  impure. 

When  the  distillation  is  completed  separate  the 
aqueous  portion  from  the  tar  and  distil  the  for- 
mer from1  a  flask  connected  with  a  Hempel  col- 
umn of  glass  beads  (Fig.  i8A).  The  tar  is  also 
heated  to  140°  in  an  oil-bath  and  any  distillate 
obtained  is  mixed  with  the  aqueous  portion 
and  distilled  with  that.  Any  oil  which  separates 
from  the  distillate  is  separated  by  means  of  a 
separatory  funnel  (p.  127).  Repeat  the  distilla- 
tion a  second  time  to  secure  as  complete  a  separa- 
tion from  the  tar  as  possible.  Unite  the  aqueous 
distillates  in  an  Erlenmeyer  flask  and  neutralize 
them  with  a  thick  paste  of  calcium  hydroxide 
added  in  small  portions,  cooling  after  each  addi- 
tion and  determining  the  end  of  the  neutraliza- 
tion by  means  of  litmus  paper.  Filter  on  a 
moistened  filter  from  some  tar  which  separates 
and  from  impurities  of  the  lime  which  remain. 
Distil  the  filtrate,  adding  some  pieces  of  porous 
porcelain  to  prevent  bumping  and  collecting  the 
distillate  in  three  of  four  fractions,  stopping  the 
distillation  when  the  temperature  reaches  100°. 
Fractionate  the  distillate  systematically  to  sepa- 
rate the  methyl  alcohol  and  acetone.  The  crude 
Fig.  ISA.  methyl  alcohol  may  be  freed  from  acetone 

by  means  of  sodium  hydrogen  sulphite.     The  acetone  may  also 


GENERAI,  OPERATIONS  37 

be  converted  into  the  double  compound  with  acid  sodium  sul- 
phite (p.  92). 

Evaporate  the  residue  from  which  the  methyl  alcohol  and 
acetone  have  been  distilled  and  obtain  from  it  ordinary  gray 
calcium  acetate. 


Chapter  III 

HYDROCARBONS 

Hydrocarbons  may  be  prepared  by  distilling  salts  of  acids 
with  soda-lime  or  barium  hydroxide,  or  in  some  cases,  with  sod- 
ium methylate  (Mai:  Ber.,  22,  2133.) 

RCO2Na  +  NaOH  =  RH  +  Na2CO3. 

A  second  method  consists  in  treating  halogen  derivatives  ot 
the  hydrocarbons  with  sodium,  usually  in  ethereal  solution,  or 
with  zinc  alkyl  compounds. 

RI  4-  R'i  _j_  2Na  =  R  —  R'  -j-  2NaI. 

-D/ 

2RI  +  Zn/       =  2R  —  R'  -f  ZnL. 
>&' 

These  methods  are  of  especial  value  for  the  determination  of 
structure. 

A  somewhat  related  method  consists  in  treating  a  mixture  of 
an  aromatic  hydrocarbon  and  an  alkyl  chloride,  bromide,  or 
iodide  with  dry  aluminium  chloride  (Friedel  and  Crafts).  This 
method  of  synthesis  loses  very  much  in  value  from  the  fact  that 
side  chains  of  aromatic  hydrocarbons  may  be  removed  by  the 
action  of  aluminium  chloride,  and  rearrangements  are  liable  to 
result.  As  an  illustration  of  the  reaction,  the  synthesis  of  tri- 
phenyl  methane  may  be  given. 

C6H5X 

3C6H6  -f  CHC13  +  Aid,  =  C6H5— CH  -f  3HC1  -f  Aid.. 

C  H  ' 

^6^5 

The  reaction  appears  to  give  at  first  a  compound  of  aluminium 
chloride  with  the  hydrocarbon,  C6H5A1C12,  and  this  compound 
then  reacts  with  the  chloroform  forming  triphenylmethane  and 
regenerating  the  aluminium  chloride. 

Alcohols  are  usually  converted  into  unsaturated  hydrocarbons 
when  treated  with  concentrated  sulphuric  acid,  (see  7,  p.  44) 


HYDROCARBONS  39 

or  zinc  chloride,  or  they  may  be  converted  indirectly,  by  the 
preparation  from  them  of  a  halogen  alkyl,  and  treatment  of  the 
latter  with  alcoholic  potash. 

/OH  /HSO, 

R"<  +  H2S04  =  R"<  +  H20. 

\H  XH 


A 

R< 
\H 


-  R"  +  H2SO,. 


KOH  =  R"  -t-  KI  H-  H2O. 


In  some  cases  quinoline  may  be  used  with  advantage  in  place 
of  alcoholic  potash.  (Baeyer:  Ber.,  25,  1840,  2122.) 

Monohalogen  derivatives  of  hydrocarbons  may  be  reduced  to 
the  hydrocarbon,  the  reducing  agents  most  commonly  used  being 
cencentrated  hydriodic  acid;  the  copper  zinc  couple  in  the  pres- 
ence of  alcohol  or  water  (Gladstone  and  Tribe:  Ber.,  6,  202, 
454,  1136;  J.  Chem.  Soc.,  1884,  154);  zinc  in  water  at  150°- 
160°  (Frankland:  Ann.,  71,  203;  74,  41);  and  aluminum  chlo- 
ride at  i2O°-i5o°  (Kohnlein:  Ber.,  16,  560;  Kluge:  Ann.,  282, 
214.)  The  author  has  found  that  Kohnlein's  method  gives  a 
mixture  of  compounds  when  applied  to  isobutyl  iodide.  The 
iodides  are  more  suitable  than  other  halogen  derivatives  for  these 
reactions. 

RI  +  HI  =  RH  +  I2. 

/R 
2RI  -f-  2Zn  =  Zn<       -f-  Znl.,. 


/ 
=  Zn< 

\R 


Zn<       -f  2Ht£)  —  Zn(OH)2  +  ?RH. 


Compounds  having  two  halogea  atoms  combined  with  adjacent 
carbon  atoms,,  lose  both  bromine  atoms  with  the  formation  of  an 
unsaturated  hydrocarbon  on  treatment  with  sodium,  or  with 
zinc  dust  and  acetic  acid,  or  with  mercuric  iodide,  or  lead  iodide. 

Under  the  influence  of  condensing  agents,  such  as  concen- 
trated sulphuric  acid,  zinc  chloride,  and  phosphorus  pentoxide, 


4O  ORGANIC   CHEMISTRY 

or  pentasulphide,  ketones,  aldehydes,  and  sometimes  other  com- 
pounds, frequently  condense  to  form  hydrocarbons.  In  this  way 
mesitylene  is  formed  from  acetone,  and  cymene  from  the  open 
chain  aldehyde,  geranial.  (Semmler:  Ber.,  23,  2965;  24,  205.) 
The  formation  of  cymene  from  camphor  is  analogous  in  some  re- 
spects, but  involves  a  separation  of  two  carbon  atoms  instead 
of  a  condensation. 

A  great  variety  of  hydrocarbons,  especially  methane,  olefmes, 
acetylene,  and  aromatic  hydrocarbons,  are  formed  by  heating  or- 
ganic compounds  to  high  temperatures. 

Aromatic  hydrocarbons  may  be  reduced  to  "alicyclic"  com- 
pounds by  reduction  with  hydriodic  acid  at  high  temperatures, 
or,  sometimes,  by  means  of  amyl  alcohol  and  sodium.  Zelinsky 
has  shown,  however,  that  hydriodic  acid  at  high  temperatures 
transforms  cyclohexane  into  methyl  cyclopentane.  (Ber.,  30, 
387.) 

G6H6  +  6HI  =  C5H9CH3  +  3I2. 
Ci0H8  +  4^  =  C6H4.C4H8. 
Naphthalene.  Naphthalene 

tetrahydride 

Benzene  may  be  reduced  to  cyclohexane  and  many  other  com- 
pounds may  take  up  hydrogen  when  heated  to  a  moderate  tem- 
perature with  hydrogen  in  the  presence  of  finely  divided  nickel. 
(Sabatier  and  Senderens,  see  n,  p.  50.)  Somewhat  similar  re- 
ductions may  be  effected  at  ordinary  temperatures  by  hydrogen 
in  the  presence  of  colloidal  palladium  or  finely  divided  platinum. 
(Ber.;  41,  1475.)  Little  has  been  said  about  the  theory  of  these 
reactions  but  it  would  seem  that  the  hydrogen  gas  is  separated 
into  hydrogen  atoms  or  ions  under  the  influence  of  the  metal. 

Ketones,  phenols,  alcohols,  and  in  some  cases  acids,  may  be 
reduced  to  hydrocarbons  by  heating  with  concentrated  hydriodic 
acid,  or  hydriodic  acid  and  phosphorus,  usually  in  sealed  tubes. 


:> 


CQ  +  4HI  =      >CH2  +  2l,  +  H20. 
R/ 

Phenols,  and  sometimes  other  oxygen  compounds,  may  be 


HYDROCARBONS  4-1 

duced  to  hydrocarbons  by  distilling  over  heated  zinc  dust,  usually 
in  a  hard  glass  tube  in  a  combustion  furnace. 

The  carbides  of  the  metals,  when  treated  with  water,  or  with 
acids,  give  hydrocarbons  which  differ  with  the  metal.  Calcium 
carbide  gives  acetylene,  aluminium  carbide  gives  methane,  iron 
carbide  chiefly  olefines.  (Moissan:  Compt.  rend.,  122,  1462.) 

Aromatic  amines  may  be  converted  into  hydrocarbons  by 
treatment  with  nitrous  acid  and  alcohol  (see  100,  p.  212).  Some- 
times, however,  the  reaction  causes  the  replacement  of  the  amine 
group  by  the  ethoxy  group,  C2H5O,  instead  of  hydrogen.  (  Ren> 
sen  and  his  co-workers:  Am.  Chem.  J.,  8,  243;  9,  387;  n,  319; 

15,   105;  IQ,   163;  20,  229.) 


5.  Preparation  of  a  Hydrocarbon  by  Distilling  the  Salt  of  an 
Acid  with  Soda-Lime. — Methane,  CH4. 

Literature — Preparation  from  sodium  acetate  and  barium  oxide,  Dumas: 
Ann.,  33,  81 ;  Ladenburg  u.  Kriigel :  Ber.,  32»  1820 ;  From  methvl  iodide, 
Gladstone  and  Tribe:  J.  Chem.  Soc.,  43,  154;  From  aluminium  carbide, 
Moissan:  Bull.  soc.  chim.,  nf  1012;  15,  1285;  Formation  from  the  ele- 
ments, Bone  and  Jerdan :  J.  Chem.  Soc.,  71*  42. 

10  grams  anhydrous  sodium  acetate. 

10  grams  soda-lime. 

Grind  together  and  mix  intimately  in  a  mortar  10  grams  of 
fused  sodium  acetate  and  10  grams  of  soda-lime.  Put  the  mixture 
in  a  100  cc.  hard  glass  retort  or  in  a  20  cm.  hard  glass  test-tube. 
Support  the  retort  or  tube  with  a  clamp  attached  to  a  retort 
stand.  Connect  by  means  of  a  delivery  tube  of  india-rubber  or 
glass  with  bottles  and  other  receptacles  filled  with  water  and  in- 
verted in  a  pan  or  dish.  Heat  the  contents  of  the  retort  or  tube 
strongly  with  a  Bunsen  burner  and  collect  the  gas  evolved,  al- 
lowing the  first  portions,  which  contain  air,  to  escape.  Per- 
form the  following  experiments  with  the  gas. 

1.  Pour  the  gas  upward  from  one  bottle  to  another.     What 
is  the  weight  of  the  gram  molecular  volume  of  the  gas  and  how 
does  the  weight  compare  with  the  weight  of  air? 

2.  Mix  with  the  amount  of  air  required  for  complete  com- 


42  ORGANIC   CHEMISTRY 

bustion  (assuming  that  air  contains  %  of  its  volume  of  oxygen) 
in  a  300  cc.,  wide  mouthed,  strong  bottle  and  explode  the  mix- 
ture. 

3.  Fill  a  test-tube  with  the  gas,  introduce  I  cc.  of  bromine  water, 
stopper  the  tube  and  expose  to  direct  sunlight,  or  for  a  longer 
time  to  diffused  daylight. 

4.  Examine  the  residue  of  the  materials  from  which  the  gas 
was  generated  for  carbonate. 

How  many  grams  of  sodium  acetate  would  be  required  to 
generate  one  gram  molecular  volume  of  methane?  How  many 
liters  should  10  grams  of  the  acetate  give? 

The  preparation  of  benzene,  p.  50,  is  the  same  in  principle  as 
that  of  methane  given  here.  The  method  may  also  be  applied 
to  salts  of  sulphonic  acids. 

6.  Preparation  of  a  Hydrocarbon  from  a  Halogen  Compound 
by  Reduction. — Ethane,  C2H6.  Determination  of  the  density. 

Literature — Identity  of  ethane  from  electrolysis  of  acetic  acid  and 
from  reduction  of  ethyl  iodide,  Schorlemmer:  Ann.,  is1,  76;  i32>  234; 
Presence  in  natural  gas,  L.  Smith:  Ann.  chim.  phys.,  8,  566;  Preparation 
from  ethyl  iodide,  Gladstone  and  Tribe:  Ber.,  6,  202;  J.  Chem.  Soc.,  45> 
154;  Properties  Ladenburg  and  Kritgel :  Ber.,  32,  1821;  Olzewsky:  Ber, 
27»  3306 ;  Hainlen :  Ann.,  282,  245. 

5  grams  powdered  zinc. 

2  per  cent,  solution  of  copper  sulphate. 

10  grams   ethyl   iodide. 

5   cc.    alcohol. 

Prepare  a  round  bulb,  as  shown  in  Fig.  19,  sealed  to  a 
three-way  stop-cock  and  having  a  capacity  of  100  to  125  cc. 
Determine  the  capacity  of  the  bulb  by  weighing  it  empty  and 
filled  with  water  at  20°  exactly  to  the  stop-cock,  using  the  di- 
rections for  calculation  given  on  p.  33.  Remove  the  water  and 
dry  the  bulb  thoroughly  by  warming  and  exhausting  it  re- 
peatedly with  a  good  filter-pump.  Finally,  when  cold,  exhaust 
the  bulb  while  connected  with  a  manometer,  measuring  the  pres- 
sure of  the  residual  air  and  the  temperature.  Place  in  the  bal- 
ance case  and  weigh,  noting  the  temperature  of  the  balance  case. 


HYDROCARBONS 


43 


Put  5  grams  of  powdered  zinc  (30  mesh,  such  as  is  used  in  the 
Jones  reductor)  in  a  20  cm.,  heavy  walled  test-tube,  add  5  cc.  of 
a  2  per  cent,  solution  of  copper  sulphate  and  shake  till  the  solu- 
tion becomes  colorless.  Pour  off  the  solution  of  zinc  sulphate, 
add  more  of  the  copper  sulphate  and  repeat  a  third  and  fourth 
time.  Finally  wash  repeatedly  by  decantation  and  once  with 
alcohol.  Cover  the  zinc  with  5  cc.  of  alcohol,  close  the  tube 
with  a  stopper  having  two  holes  through  one  of  which  passes  a 
thistle  tube  dipping  below  the  surface  of  the  alcohol  and  through 
the  other  a  delivery  tube  connected  with  two  potash  bulbs,  the 


Fig.  19. 

first  containing  alcohol  and  the  second  concentrated  sulphuric 
acid.  The  alcohol  is  to  absorb  vapors  of  ethyl  iodide  which 
might  escape  and  the  sulphuric  acid  to  remove  vapors  of  alcohol 
and  water.  Connect  the  second  bulbs  with  the  exhausted  and 
weighed  bulb  mentioned  above,  the  stop-cock  being  placed  in 
such  a  manner  that  the  first  gas  will  escape  through  the  side 
tube.  To  the  latter  is  attached  a  delivery  tube  conveying  the  gas 
to  an  inverted  bottle  for  collecting  the  gas  over  water.  From 
the  generator  to  the  weighed  bulb  all  connections  should  be  made 
by  bringing  the  glass  tubes  together  within  short,  tightly  fitting 
pieces  of  rubber  tubing. 

When  everything  is  ready,  prepare  a  mixture  of  10  grams  of 
ethyl  iodide,   5  cc.  of  alcohol  and  one  or  two  drops  of  dilute 


44  pRGANIC   CHEMISTRY 

sulphuric  acid.  Add  this  mixture  to  the  generator  through  the 
thistle  tube,  warming  very  gently  at  first,  if  necessary,  to  start 
the  reaction  but  cooling  later,  if  the  reaction  becomes  rapid. 
The  mixture  must  be  added  carefully,  in  such  a  manner  that 
bubbles  of  air  are  not  carried  down  the  thistle  tube.  Allow  about 
300  cc.  of  gas  to  collect  in  the  bottle  to  insure  the  removal 
of  the  air  in  the  apparatus,  then  turn  the  stop-cock  very  cau- 
tiously so  that  the  gas  will  enter  the  exhausted  bulb.  The 
column  of  liquid  in  the  thistle  tube  must  be  carefully  watched 
and  the  gas  must  not  pass  into  the  bulb  so  fast  that  air-  is 
drawn  down  through  it  into  the  generator.  When  no  more  gas 
will  enter  the  bulb  with  the  stop-cock  wide  open,  the  stop-cock 
is  closed  and  the  bulb  disconnected.  The  stop-cock  is  then  opened, 
momentarily,  to  allow  the  gas  within  to  come  to  atmospheric 
pressure,  care  being  taken  that  the  bulb  is  not  warmed  by  the 
hand.  The  temperature  and  barometric  pressure  are  then  noted 
fcnd  the  bulb  weighed.  From  the  results  calculate  the  weights 
of  a  liter  and  of  a  gram  molecular  volume  (22.4  liters)  of  the 
gas. 

The  method  described,  with  slight  modifications,  may  be  used 
to  replace  iodine  by  hydrogen  in  almost  any  aliphatic  compound 
or  in  aromatic  compounds  containing  iodine  in  the  side  chain, 
sometimes,  also,  when  the  iodine  is  in  the  nucleus.  Since  al- 
coholic hydroxyl  in  alcohols^  hydroxy  acids  and  other  compounds 
may  usually  be  replaced  by  iodine  on  treatment  with  concen- 
trated hydriodic  acid  the  method  may  often  be  used  for  the 
indirect  replacement  of  hydroxyl  by  hydrogen. 

7.  Preparation  of  a  Hydrocarbon  of    the    Ethylene    Series. — 

CH2Br 

Ethylene  dibromide,      |  (dibrom  (1.2)  ethane). 

CH2Br 

Literature — Balard:  Ann  chim.  phys.  [2],  32,  375  (1826);  Erlenmeyer 
and  Bunte:  Ann.,  168,  64;  192,  244;  Denzel :  Ibid,  195,  210;  Thorpe:  J. 
Chem.  Soc.,  37,  1/7  (1880);  Anschiitz:  Ann.,  221,  137;  V.  Meyer  u. 
Miiller:  Ber.,  24,  4249;  Tawildarow:  Ann.,  176,  12;  Use  of  phosphoric 
acid,  Newth:  J.  Chem.  Soc.,  79,  915;  Theory  for  the  formation  of  ether 
and  ethylene,  Nef :  Ann.,  309,  141  ;  318,  50. 


HYDROCARBONS  45 

30  cc.  alcohol. 

50  cc.   sulphuric   acid    (1.84). 

50  cc.  alcohol. 

50  cc.  sulphuric  acid. 

20  cc.   (60  grams)  bromine. 

Put  30  cc.  of  alcohol  in  a  liter  flask.  Add  50  cc.  concentrated 
sulphuric  acid.  Arrange  a  flask  as  shown  in  Fig.  20  with  a 
thistle  tube  bearing  a  stopper  with  a  separatory  funnel  having 
a  short  stem.  By  this  arrangement  the  rate  at  which  the  con- 
tents of  the  funnel  is  dropped  into  the  mixture  can  be  seen  and 
regulated.  The  lower  end  of  the  thistle  tube  should  be  drawn  out 
to  a  diameter  of  about  2  mm.  for  about  10  cm.  and  then  bent  back 
twice  on  itself  as  shown  in  Fig.  20.  If  this  is  properly  done  the 
tube  will  still  pass  through  the  hole  of  a  rubber  stopper,  and  a  uni- 
form, slow  delivery  from  the  end  of  the  tube  can  be  secured.  Con- 
nect with  a  wash-bottle  containing  caustic  soda,  and  with  a  second 
wash-bottle  containing  concentrated  sulphuric  acid  and  having 
a  safety-tube,  then  with  a  thick  walled  tube  about  15  mm.  in 
diameter,  fitted  with  tubes  like  a  wash-bottle  and  containing 
20  cc.  of  bromine  covered  with  a  little  water.  The  latter  should 
be  placed  in  cold  water  and  connected  with  a  tube  opening  just 
above  the  surface  of  a  sodium  hydroxide  solution  in  a  large 
bottle.  Place  the  generating  flask  on  a  thin  asbestos  paper, 
and  heat  till  the  thermometer  (not  shown  in  the  figure)  in 
the  mixture  reaches  I7O°-I75°.  It  is  an  advantage  to  heat  mo- 
mentarily to  i85°-i9O°  and  then  allow  the  mixture  to  fall  back 
to  the  temperature  specified.  When  the  evolution  of  ethylene 
has  well  begun,  drop  in  slowly  a  mixture  of  50  cc.  of  alcohol 
with  50  cc.  of  concentrated  sulphuric  acid,  keeping  the  tempera- 
ture at  about  170°.  Continue  the  passage  of  the  gas  till  the 
bromine  becomes  nearly  colorless.  The  mixture  in  the  generat- 
ing flask  should  not  carbonize.  If  it  should  do  so,  from  too  rapid 
heating,  it  is  usually  best  to  empty  the  flask  and  put  in  a  new 
mixture  of  alcohol  and  acid.  Transfer  the  ethylene  bromide  to 
a  separatory  funnel,  add  some  water  and  agitate  gently,  separate, 
add  a  dilute  solution  of  sodium  hydroxide  to  alkaline  reaction, 


46  ORGANIC   CHEMISTRY 

shaking  gently  with  care  not  to  form  an  emulsion  and  draw  off 


Hg.  20. 


into  a  dry  flask.     Drops  of  the  ethylene  bromide  often  remain 
floating  on  top  of  the  liquid.     These  can  sometimes  be  caused 


HYDROCARBONS 


47 


to  settle  by  gentle  agitation  but  it  is  usually  best  to  fill  the  sep- 
aratory  funnel  nearly  full  with  water  to  lessen  the  area  of  the 
upper  surface  and  make  it  easier  to  shake  down  the  heavier  liq- 
uid. Add  some  fus.ed  calcium  chloride  and  allow  tcjystand  for 


NfiOH 


sometime  to  dry  the  liquid.  Filter  into  a  dry  distilling  bulb, 
and  distil.  The  yield  is  nearly  equal  to  the  weight  of  the  bro- 
mine used. 

Ethylene  bronrde  solidifies  at  a  low  temperature  and  melts  at 
9.5°.  It  boils  at  130.3°,  and  has  a  specific  gravity  of  2.1785  at 
20°.  When  warmed  in  alcoholic  solution  with  granulated  zinc, 
ethylene  is  regenerated.  With  alcoholic  potash  vinyl  bromide 
and  acetylene  are  formed.  Other  compounds  having  two  halogen 
atoms  combined  with  adjacent  carbon  atoms  react  in  a  similar 
manner. 

8.  Preparation  of  a  Hydrocarbon  from  a  Carbide.— Acetylene, 

CH  =  CH. 

Literature. — Preparation  of  carbides,  Moissan :  Bull.  soc.  chim.  (3), 
n»  1002,  1010;  Preparation  of  hydrocarbons  from  carbides,  Wohler:  Ann., 
124,  220;  Moissan:  Bull.  soc.  chim.,  n,  1012;  i5»  1285;  Ber.,  4°»  5120; 
W.  E.  Gibbs:  Acetylene  Gas,  its  Production  and  Use;  London,  1898; 
Composition  of  copper  and  silver  acetylides,  Keiser:  Am.  Chem.  J.,  14* 
285;  Soderbaum:  Ber.,  30,  760;  Explosion  of  acetylene  as  an  endothermic 
compound,  Berthelot,  Vielle :  Compt.  rend.,  i23»  523 ;  Ann.  chim.  phys.,  (7,) 


48  ORGANIC   CHEMISTRY 

XI»  55  Comparative  safety  of  acetylene  in  acetone,  Claude,  Hess:  Compt. 
rend.,  124,  626;  Berthelot,  Vieille:  Compt.  rend.,  124,  988,  996,  1000.  See 
also  the  following  preparation. 

10  grams  of  calcium  carbide. 
Water. 

1  gram  cuprous  chloride. 

5  cc,  ammonium  hydroxide   (10  per  cent.  NH3.) 
20  cc.  water. 

0.2  gram  silver  nitrate. 

2  cc.  ammonium  hydroxide. 
10  cc.  of  water. 

Put  10  grams  of  calcium  carbide  in  a  200  cc.  flask.  Fit  the 
flask  with  a  stopper  bearing  a  separatory  funnel  and  a  delivery 
tube.  From  the  separatory  funnel  drop  water  slowly  upon  the 
carbide  and  conduct  the  gas  through  a  solution  of  one  gram 
of  cuprous  chloride  dissolved  in  dilute  ammonium  hydroxide, 
also  through  a  solution  of  0.2  gram  of  silver  nitrate  (2  cc.  of  a 
10  per  cent,  solution)  dissolved  in  dilute  ammonium  hydroxide. 
Filter  off  the  precipitates,  transfer  them  to  dry  filter-paper  and 
allow  to  dry  in  the  air.  Explode  portions  of  the  precipitate  by 
heating  over  the  flame  on  a  piece  of  tin  foil  or  sheet  iron,  using 
very  small  amounts  for  the  first  trials.  Destroy  all  of  the  pre- 
cipitates by  explosion  or  treating  with  dilute  acids  before  leaving 
the  laboratory. 

If  an  acetylene  burner  is  available,  the  illuminating  quality  of 
the  gas  may  be  tested  after  all  of  the  air  has  been  expelled 
from  the  generator.  This  may  be  determined  by  collecting  some 
of  the  gas  in  a  test-tube  and  seeing  whether  it  explodes  on  the 
application  of  a  flame. 

Acetylene  is  better  generated  on  a  larger  scale  by  dropping 
the  carbide  into  water  and  this  plan  is  adopted  in  the  better 
forms  of  generators.  Why?  How  many  liters  of  acetylene 
should  10  grams  of  calcium  carbide  yield? 

.Acetylene  tetrabromide  may  be  prepared  by  passing  acetylene 


HYDROCARBONS  49 

into  bromine  as  described  on  p.  45  for  preparing  ethylene  bromide. 
It  must  be  distilled  under  diminished  pressure,  however. 

9.  Preparation  of  a  Hydrocarbon  by  Decomposition  of  a  Halo- 
gen Compound  with  Sodium  Ethylate.— Acetylene,  CH  =  CH. 

Literature. — Formation  by  incomplete  combustion  of  illuminating  gas, 
Rieth:  Z.  f.  Chemie,  1867,  599;  By  direct  union  of  carbon  and  hydrogen, 
Berthelot:  Ann.  chim  phys.,  (4),  13*  143;  From  vinyl  bromide  or  ethylene 
bromide  and  alcoholic  potash,  Sawitsch:  J.,  1861,  646;  Sabanejew:  Ann., 
i78»  in  ;  By  passing  ethylene  chloride  over  heated  soda-lime,  Wilde:  Ber., 
7»  352;  By  reduction  of  tetrachlorethane  with  zinc,  Sabanejew:  Ann.,  216, 
262 ;  By  electrolysis  of  f umaric  or  maleic  acid,  Kekule :  Ann.,  is1!  85 ;  See 
also  the  preceding  preparation. 

5  grams  sodium. 

60  cc.  absolute  alcohol. 

10  grams  ethylene  bromide. 

Connect  a  200  cc.  flask  with  an  upright  condenser  making 
sure  that  the  connection  is  gas  tight.  A  rubber  stopper  may  be 
used.  Put  in  the  flask  5  grams  of  clean  metallic  sodium  from 
which  the  outer  crust  has  been  cut  with  a  knife.  The  shavings 
of  sodium  must  be  put  in  the  bottle  kept  for  the  purpose.  It  is 
dangerous  to  throw  them  into  a  slop  jar  or  a  sink.  Pour  through 
the  condenser,  in  portions,  60  cc.  of  absolute  alcohol.  This  may 
be  all  added  within  5  to  10  minutes  but  the  reaction  should  not 
be  allowed  to  become  violent.  After  the  alcohol  has  all  been  added, 
boil  gently  on  a  wire  gauze  covered  with  asbestos  till  the  sodium 
is  all  dissolved.  Allow  to  cool,  connect  the  top  of  the  condenser 
with  a  small  U-tube  containing  alcohol  (to  absorb  some  vinyl 
bromide,  which  will  escape)  and  from  that  to  a  U-tube  or  small 
flask  containing  a  solution  of  I  gram  of  cuprous  chloride  in  25 
cc.  of  dilute  ammonium  hydroxide  or  0.2  gram  silver  nitrate  in 
the  same  solvent.  Pour  TO  grams  of  ethylene  bromide  through 
the  condenser  into  the  cooled  solution  of  sodium  ethylate  and 
warm  gently  to  cause  a  slow  evolution  of  acetylene.  Perform 
the  experiments  with  the  copper  acetylide  and  silver  acetylide 
which  are  described  in  the  preceding  preparation. 

From  the  alcohol  in  the  U-tube  a  small  amount  of  vinyl  bromide 
may  be  precipitated  by  adding  crushed  ice  and  water.  The 
4 


50  ORGANIC    CHEMISTRY 

vinyl  bromide  boils  at  16°  and,  of  course,  becomes  a  gas  at  ordi- 
nary temperatures. 

The  action  of  the  sodium  ethylate  in  this  preparation  is  simi- 
lar to  the  action  of  alcoholic  potash  upon  almost  any  aliphatic 
halogen  compound  in  which  the  grouping  >CH  —  CBr  (Cl,  I)< 
occurs,  the  halogen  being  removed  along  with  a  hydrogen  atom 
which  is  attached  to  the  carbon  atom  adjacent  to  the  one  bearing 
the  halogen. 

Metallic  compounds  analogous  to  the  copper  acetylide  (more 
properly  called  copper  carbide)  are  formed  from  all  derivatives 
of  acetylene  having  the  grouping  — C  =  CH  but  not  from  com- 
pounds of  the  type  R  —  C  =  C  —  R. 

10.  Preparation  of  a  Hydrocarbon  by  Distillation  of  a  Salt  of 
an  Acid  with  Soda-Lime. — Benzene,  C6H6.     (Phen.) 

Literature — Mitscherlich :  Ann.,  9>  39;  Marignac:  Ibid,  42»  217;  Wohler : 
Ibid,  51,  146;  Berthelot:  Ann.  chim.  phys.  [4],  9>  469;  Hofmann  :  Ber.,  4, 
163;  Baeyer:  Ibid,  12.  1311;  V.  Meyer:  Ibid,  16,  1465. 

20  grams  benzoic  acid. 

40  grams  soda-lime.  ,. 

Mix  20  grams  of  benzoic  acid  with  40  grams  of  soda-lime 
by  grinding  together  in  a  mortar.  Put  the  mixture  in  a  small 
flask,  connect  with  a  condenser,  and  distil  over  the  free  flame. 
Separate  the  benzene  from  the  water,  dry  it  with  calcium  chlo- 
ride, and  distil.  If  perfectly,  dry  benzene  is  desired,  distil  it  a 
second  time  over  metallic  sodium.  Yield  8  to  9  grams. 

Benzene  solidifies  at  a  low  temperature,  and  melts  at  5.40°. 
It  boils  at  80.12°. 

This  method  of  preparation  is  no  longer  practically  used,  but 
it  was  of  very  great  importance  in  the  early  study  of  the  aro- 
-  matic  hydrocarbons,  and  illustrates  a  method  very  general  in  its 
application. 

11.  Reduction  of  a  Hydrocarbon  by  Hydrogen  in  the  Presence 
of    Finely    Divided    Nickel.     Sabatier's    Method. — Cyclohexane, 
CH2  —  CH2  —  CH., 

I  I     "- 

CH,  —  CH.  —  CH2 


HYDROCARBONS  5 I 

Literature — Application  of  the  method  to  a  great  variety  of  substances, 
Sabatier  and  Senderens :  Ann.  chim.  phys.  (8),  4,  319-488;  Compt.  rend., 
132,  210,  566;  Chem.  Centrbl.,  '01,  I,  501,  817;  '05,  I,  1004,  1317;  Reduction 
of  phenol  to  cyclohexanol,  Sabatier  and  Senderens:  Compt.  rend.,  i37» 
1025 ;  Structure  of  the  hydrocarbon  formed  by  reduction  of  benzene  by 
hydriodic  acid,  Kijner:  J.  prakt.  Chem.  (2),  56,  364;  Description  of  pro- 
cess, Henle:  Anleitung  fur  das  organisch  praparative  Praktikum,  p.  79. 

Preparation  of  Finely  Divided  Nickel 

Break  some  porous  porcelain  plates  into  pieces  3  to  5  mm. 
in  diameter  and  separate  them  from  the  dust  by  means  of  a  sieve. 
Pour  over  them  in  a  flat  dish  a  concentrated  solution  of  nickel 
nitrate  and  evaporate  on  the  water-bath  to  dryness,  with  f recfuent 
stirring.  When  dry,  transfer  to  a  nickel  crucible  and  heat  over 
the  free  flame  till  no  more  oxides  of  nitrogen  are  evolved.  Fill 
a  tube  of  hard  glass,  about  one  meter  long  and  2  cm.  in  diameter 
with  the  pieces,  putting  some  pieces  of  broken  marble  at  each 
end  to  hold  them  in  place.  Draw  out  one  end  of  the  tube  and 
bend  it  downward  or  correct  with  an  adapter  as  shown  in  Fig.  22. 
Place  the  tube  in  a  combustion  furnace  inclined  at  an  angle 
so  that  the  water  formed  by  reduction  of  the  nickel  oxide -will 
run  away  at  the  lower  end,  and  heat  at  about  500°  (measured 
with  a  thermometer  filled  with  nitrogen  or  carbon  dioxide  above 
the  mercury)  in  a  rapid  current  of  pure  hydrogen  for  several 
hours  until  water  no  longer  condenses  in  the  delivery  tube  con- 
nected with  the  lower  end.  The  end  of  the  delivery  tube  should 
dip  under  concentrated  sulphuric  acid  to  prevent  diffusion  of  air, 
as  only  nickel,  which  has  been  freshly  reduced  at  not  too  high 
a  temperature  and  afterwards  portected  from  the  air,  is  effective. 
Cool  in  a  slow  current  of  hydrogen. 

Arrange  the  apparatus  shown  in  the  figure  so  that  the  hydrogen 
from  the  Kipp  generator  passes  first  through  a  concentrated 
solution  of  potassium  permanganate,  then  through  concentrated 
sulphuric  acid,  then  through  a  distilling  bulb  containing  50 
grams  of  benzene.  The  latter  is  placed  in  a  beaker  of  water 
which  can  be  warmed.  Before  warming,  however,  and  before 
connecting  the  apparatus  with  the  tube  containing  the  reduced 
nickel  the  hydrogen  is  allowed  to  pass  long  enough  to  expel  air 


ORGANIC   CHEMISTRY 


HYDROCARBONS  53 

from  the  apparatus.  The  tube  containing  the  nickel  is  placed 
in  a  Volhard '  bath  (Ann.,  284,  235)  filled  with  high  boiling 
gasoline  or  kerosene  which  is  set  to  maintain  a  temperature 
of  195°  by  distilling  away  the  low  boiling  portion  till  that 
temperature  is  reached  in  the  bath.  When  the  air  has  been 
expelled,  connect  the  delivery  tube  of  the  distilling  bulb  con- 
taining the  benzene  with  the-  tube  containing  the  nickel  and  con- 
nect the  lower  end  of  the  latter  to  a  tube  reaching  just  below 
the  neck  in  a  200  cc.  distilling  bulb  surrounded  with  ice  water. 
The  side  tube  of  this  bulb  is  connected  to  a  tube  dipping  into 
25  cc.  of  alcohol  contained  in  a  second  distilling  bulb,  which. is 
also  surrounded  with  ice  water.  The  alcohol  is  to  retain  vapors 
of  cyclohexane  which  escape  condensation  in  the  first  bulb. 

Maintain  the  temperature  of  the  bath  containing  the  tube  with 
the  nickel  at  195°,  that  of  .the  water  in  the  beaker  surrounding 
the  benzene  at  35°.  At  the  latter  temperature  the  vapor  pressure 
of  benzene  is  about  145  mm.  If  the  hydrogen  is  saturated  with 
benzene  vapor  at  that  vapor  pressure,  what  per  cent,  excess  of 
hydrogen  will  be  used?  The  hydrogen  may  pass  at  such  a  rate 
that  the  bubbles  may  be  easily  counted.  After  six  or  eight 
hours  30  to  40  grams  of  cyclohexane  should  have  collected  in 
the  bulb  surrounded  with  ice-water.  A  few  grams  additional 
may  be  obtained  by  diluting  the  alcohol  contained  in  the  second 
bulb.  The  precipitated  hydrocarbon  is  mixed  with  the  rest  and 
the  whole  shaken,  by  means  of  a  shaking  machine,  with  an  equal 
volume  of  fuming  sulphuric  acid  containing  10  to  14  per  cent, 
of  sulphur  trioxide.  This  will  convert  unchanged  benzene  into 
benzene  sulphonie  acid  which  dissolves  easily  in  water.  Pour 
carefully  into  4  or  5  volumes  of  cold  water,  cooling  after  each 
addition.  Separate  cyclohexane  by  means  of  a  separatory  fun- 
nel, dry  with  calcium  chloride  and  distil.  Yield  70  to  80  per 
cent,  of  the  weight  of  benzene  used. 

Cyclohexane  boils  at  81°  and  freezes  at  a  low  temperature, 
melting  at  4.7°. 

Test  the  cyclohexane  for  benzene  by  warming  on  the  water- 
bath  in  a  test-tube  a  few  drops  with  a  mixture  of  3  cc.  of  con- 


54  ORGANIC    CHEMISTRY 

centrated  sulphuric  acid  and  3  cc.  of  nitric  acid  (sp.  gr.  1.42). 
Dilute  with  water,  add  a  little  ether,  shake,  allow  the  ether  to 
rise  to  the  top  and  transfer  it  to  a  dry  test-tube  by  means  of  a 
pipette  with  a  rubber  tube  attached.  (Fig.  23).  Evaporate  the 
ether,  by  dipping  the  tube  in  a  water-bath,  add  i  cc.  of  concen- 
trated hydrochloric  acid  and  a  piece  of  tin.  After  warming 
a  short  time,  dilute  slightly,  add  a  solution  of  sodium  hydroxide 
in  excess,  extract  with  ether  as  before,  and  evaporate  in  a  dry 
test-tube.  Test  the  residue  for  aniline  by  dissolving  in  water 


Fig.  23. 

and  adding  a  filtered  solution  of  chloride  of  lime.  .  Try  the  same 
test  with  a  drop  of  pure  benzene. 

The  method  of  reduction  discovered  by  Sabatier  may  be  ap- 
plied to  a  great  variety  of  substances,  and  has  made  some  sub- 
stances which  were  formerly  very  difficult  to  obtain  comparatively 
easily  accessible. 

12.  Preparation  of  Hydrocarbons  by  Means  of  Halogen 
Compounds  and  Sodium.  Fittig's  Synthesis. — Paraxylene. 

/CH3  (i). 

C6H/  ( i  .4-Dimethylphen. ) 

XCH3  (4). 

Literature. — Synthesis  from  />-bromotoluene,  Fittig,  Glinzer :  Ann., 
I36,  303;  Jannasch:  Ibid,  i?1*  79;  Ber.,  10,  1356;  From  dibromo- 
benzene:  V.  Meyer:  Ber.,  3>  753;  Preparation  from  coal  tar  through 


HYDROCARBONS  55 

the    sulphonic    acid;    Jacobsen  :    Ibid,    10,    1009,    1356;    Crafts:    Z.    anal. 
Chem.,  32,  243;   Compt.  rend.,   114*  mo. 


35  grams  parabromotoluene. 
35  grams  methyl  iodide. 
12  grams  sodium  wire. 
loo  cc.  ether. 


Press  into  a  200  cc.  flask  12  grams  of  sodium  in  the  form 
of  wire,  add  100  cc.  of  dry  ether  (see  76,  p.  175),  place  the 
flask  in  ice-water,  connect  with  an  upright  condenser,  and  add 
through  the  latter  a  mixture  of  35  grams  of  parabromotoluene, 
and  35  grams  of  methyl  iodide.  Allow  the  mixture  to  stand 
over  night,  or  till  the  reaction  appears  to  be  complete.  Distil 
off  the  ether  on  the  water-bath,  and  distil  the  hydrocarbons 
formed  over  the  free  flame.  Remove  the  remainder  of  the  ether 
from  the  oil,  by  allowing  it  to  stand  in  a  crystallizing  dish  for 
half  an  hour  in  vacua  over  sulphuric  acid.  Fraction  repeatedly 
from  a  small  distilling  bulb,  using  test-tubes  to  collect  the  dis- 
tillates, and  avoiding  loss,  as  far  as  possible.  Collect  as  much  as 
possible  of  the  paraxylene,  within  an  interval  of  2  to  3  degrees. 
Cool  this  portion  with  ice,  or  in  a  freezing  mixture,  and  pour 
off  the  part  which  does  not  solidify.  Yield  5  to  7  grams. 

The  residue  in  the  flask  will  contain  free  sodium  and  should 
be  treated  with  alcohol  to  destroy  this  and  then  with  water.  It 
must  never  be  allowed  to  stand  or  be  thrown  into  a  slop  jar  with- 

out this. 

Paraxylene  melts  at  15°,  boils  at  138°,  and  has  a  specific  gravity 
of  0.880  at  o°.  It  is  oxidized  by  dilute  nitric  acid  to  paratoluic 
acid,  and  by  the  chromic  acid  mixture  to  terephthalic  acid. 

This  synthesis  by  means  of  halogen  compounds  and  sodium, 
known  as  the  Fittig  synthesis,  has  been  very  useful  in  de- 
termining the  structure  of  halogen  derivatives  and  of  hydrocar- 
bons. 

In  some  cases  when  the  reaction  takes  place  slowly  or  not  at 
all  it  may  be  catalyzed  by  means  of  a  little  dry  ethyl  acetate. 


56  ORGANIC   CHEMISTRY 

13.  Preparation   of   a  Hydrocarbon  from  Camphor. — Cymene, 

/CH3  (i) 
yCH< 

C6H/  XCH3  (p  Methyl-isopropylphen.) 

XCH3  (4) 

Literature — Occurrence,  Gerhardt  and  Cahours:  Ann.,  38,  71,  101,  345; 
Preparation  from  camphor,  Gerhardt :  Ibid,  48>  234 ;  Dumas,  Delaland :  Ibid, 
38,  342;  by  Fittig's  synthesis,  Sylva :  Bull.  soc.  chim.,43»  321;  Jacobsen: 
Ber.,  12,  430;  Widman:  Ibid,  24,  450;  From  turpentine,  Kekule:  Ibid,  6, 
437;  Detection  in  terpenes,  Hartley:  J.  Chem.  Soc.,  37»  676;  Molecular 
rearrangements  in  the  formation  of  cymene,  Noyes:  J.  Am.  Chem.  Soc., 
3i,  13/2. 

30  grams  camphor. 

30  grams  phosphorus  pentoxide. 

Mix  intimately  in  a  flask  30  grams  of  camphor,  and  30  grams 
of  phosphorus  pentoxide.  Connect  with  a  condenser,  and  heat 
in  an  oil-bath  as  long  as  cymene  distils.  Add  to  the  cymene  a 
little  phosphorus  pentoxide,  and  boil  a  short  time  with  an  upright 
condenser.  Pour  off,  and  repeat  a  second  ti-ne.  Then  boil  the 
cymene  with  some  sodium  for  a  short  time,  using  an  upright 
condenser,  and  finally  distil.  Yield  15  to  17  grams. 

Cymene  boils  at  175°,  and  has  a  specific  gravity  of  0.8525  at 
25°.  Potassium  permanganate  oxidizes  it  to  hydroxypropylben- 

/CH, 
/COH/ 

zoic  acid,  C6H4<^  CH3  ;  the  chromic  acid  mixture  to  tere- 

XC02H 

phthalic  acid;  dilute  nitric  acid  to  par?toluic  acid. 

14.  Determination  of  a  Hydrocarbon  by  a  Pyrogenic  Reaction. — 

Diphenyl,  C6H5  —  C6H,5. 

Literature — Preparation  by  Fittig's  syntheses,  Fittig:  Ann.,  121,  363; 
From  benzene  at  a  high  temperature,  Berthelot:  Z.  anal.  Chem.,  1866, 
707 ;  La  Coste,  Sorger :  Ann.,  230,  5 ;  From  phthalic  anhydride  and  lime, 
Anschiitz,  Schultz :  Ann.,  196,  48;  From  benzene  and  tin  tetrachloride  at 
a  high  temperature,  Aronheim:  Ber.,  9,  1898;  Smith:  Ibid,  12,  722;  Z. 
Elektrochemie,  7»  903. 

200  cc.  benzene. 

Fill  the  central  portion  of  an  iron  tube,  2  cm.  in  diameter,  and 


HYDROCARBONS  57 

about  50  cm.  longer  than  the  combustion  furnace,  with  broken 
pumice.  Connect  with  one  end  of  the  tube,  by  means  of  a  per- 
forated cork,  a  tube  15  mm.  in  diameter,  which  is  drawn  out 
at  one  end  and  bent  at  right  angles.  Into  the  wider  portion  of 
the  tube,  which  is  bent  upward,  fit  a  cork  bearing  a  separatory 
funnel  in  such  a  way  that  the  benzene  can  be  seen  as  it  drops 
from  the  end  of  the  funnel.  Raise  this  end  of  the  combustion 
furnace  about  two  inches  higher  than  the  other.  Connect  the 
other  end  of  the  iron  tube  with  a  small  condenser,  by  means  of 
a  cork  and  glass  tube.  Drop  benzene  from  the  separatory  funnel 
at  the  rate  of  about  15  drops  per  minute,  heating  the  central  por- 
tion of  the  tube  to  dull  redness.  When  200  cc.  of  benzene  have 
been  dropped  into  the  tube  in  this  manner,  distil  the  distillate, 
and  return  to  the  separatory  funnel  the  part  boiling  below  120°. 
Repeat  till  a  considerable  quantity  of  high  boiling  products  has 
been  obtained.  The  benzene  condenses  with  evolution  of  hy- 
drogen. 

2C6H6  =  C6H5.C6H5  +  2H. 

Fractionate  the  product  and  crystallize  from  alcohol  the  por- 
tion boiling  from  235°-3OO°. 

Diphenyl  crystallizes  in  leaflets,  which  melt  at  70°.  It  boils  at 
254°,  and  dissolves  in  10  parts  of  alcohol  at  20°. 

15.  Preparation  of  a  Hydrocarbon  by  the  Reduction  of  a  Ke- 
tone  with  Hydriodic  Acid.— Diphenylmethane,  C6H5CH,2C6H5. 

Literature — Preparation  by  reducing  benzophenone  with  hydriodic 
acid  and  phosphorus,  Graebe:  Ber.,  7>  1624;  With  zinc  and  sulphuric  acid, 
Zincke,  Thorner :  Ber.,  .10,  1473 ;  With  zinc  dust,  Staedel :  Ann.,  iQ4,  307 ; 
From  benzyl  chloride  and  benzene  with  zinc  dust,  Zincke:  Ibid,  i59»  374; 
By  Friedel  and  Crafts  reaction,  Friedel,  Crafts:  Ann.  chim.  phys.  [6], 
i,  478;  E.  and  O.  Fischer:  Ann.,  iQ4i  253;  By  condensing  methylal  with 
benzene,  Baeyer:  Ber.,  6,  221. 

10  grams  benzophenone. 

12  grams  hydriodic  acid   (boiling-point   127°). 

2.2  grams  red  phosphorus. 

Put  in  a  tube  15  mm.  in  diameter,  and  with  walls  2  mm.  thick, 
10  grams  of  benzophenone,  12  grams  of  hydriodic  acid  (boiling- 


58  ORGANIC   CHEMISTRY 

point  127°),  and  2.2  grams  of  red  phosphorus.  Seal  caretully 
(see  p.  20),  and  heat  for  6  hours  at  160°  in  a  bomb  oven. 
Open  the  tube  carefully  by  softening  the  capillary  end  in  a  flame 
till  it  blows  out.  Cut  off  the  end  of  the  tube,  add  some  water 
and  ether  to  dissolve  the  hydrocarbon.  Separate  the  ethereal  so- 
lution, filter  it  from  the  red  phosphorus,  distil  off  the  ether,  and 
distil  the  diphenylmethane  from  a  small  distilling  bulb.  Yield 
8  to  8.5  grams. 

Diphenylmethane  melts  at  26° -27°,  and  boils  at  263°.  It  is 
easily  soluble  in  alcohol  and  ether.  It  has  a  specific  gravity  of 

26° 

1.0008  at  — o  . 
4 

Reduction  by  means  of  hydriodic  acid  has  been  very  often 
used  to  replace  hydroxyl  or  oxygen  with  hydrogen  in  determin- 
ing the  structure  of  compounds. 

1 6.  Synthesis  of  a  Hydrocarbon  by  Use  of  Aluminium  Chloride. 

C6H5X 

(Friedel  and  Crafts'  Reaction.)—  Triphenylmethane,  C6H5— CH. 

OH/ 

M>n5 

Literature — Preparation  from  benzylidene  chloride  and  mercury  phenyl, 
Kekule,  Franchimont:  Ber.,  5>  907;  By  Friedel  and  Crafts,  reaction, 
Friedel,  Crafts:  Ann  chim,  phys.,  [6],  i,  489;  Compt.  rend.,  84,  1450; 
Anschutz:  Ann.,  235,  208,  337;  E.  &  O.  Fischer:  Ibid,  iQ4»  352;  Allen, 
Kollicker :  Ibid,  227,  107 ;  Biltz :  Ber.,  26,  1961 ;  Linebarger :  Am.  Chem. 
J«>  X3>  557  >  Study  of  conditions  for  the  reaction,  Norris  and  McLeod : 
Am.  Chem.  J.,  26,  499 ;  Solubility  of  triphenylmethane  in  benzene,  Line- 
barger:  Am.  Chem.  J.,  i5»  46. 

200  grams  of  benzene. 

40  grams  chloroform. 

20  grams  aluminium  chloride. 

Mix  200  grams  of  benzene  with  40  grams  of  chloroform,  add 
some  fused  calcium  chloride,  and  allow  the  mixture  to  stand 
over  night.  Pour  off,  or  filter,  into  a  dry  flask,  connect  the  lat- 
ter with  an  upright  condenser  having  a  calcium  chloride  tube, 
which  is  bent  downward,  connected  with  its  top.  Weigh  in  a 
stoppered  preparation  tube  20  grams  of  aluminium  chloride,  best 


HYDROCARBONS  59 

freshly  prepared.1  Add  from  the  tube  to  the  mixture  of  chloro- 
form and  benzene  3  to  4  grams  of  the  aluminium  chloride.  Shake 
and  warm  until  the  reaction  begins;  after  five  to  ten  minutes 
add  a  second  portion  of  the  chloride,  and  add  all  of  it  in  this 
manner  in  about  thirty  minutes.  Boil  the  mixture  gently  for 
an  hour,  cool,  pour  carefully  into  200  cc.  of  water,  stir,  transfer 
to  a  separatory  funnel,  shake,  and  separate  the  oil  from  the  water, 
filter  through  a  filter  moistened  with  benzene  to  remove  water, 
distil  off  the  benzene,  and  collect  in  fractions,  below  100°,  ioo°- 
200°,  200°-300°.  Transfer  the  residue  to  a  smaller  distilling 
bulb  or  retort,  and  distil  without  a  thermometer,  or  with  a 
thermometer  filled  with  nitrogen  under  pressure,  till  the  distillate 
becomes  brown  and  viscous.  Ctystallize  from  hot  benzene,  ob- 
taining in  this  way  the  double  compound  C19H16  +  QHG,  which 
crystallizes  in  colorless  crystals,  that  melt  at  76°.  The  benzene 
can  be  expelled  by  warming  the  compound  on  the  water-bath, 
and  the  triphenylmethane  may  be  crystallized  again  from  alco- 
hol. Yield  25  to  30  grams,  if  the  aluminium  chloride  is  fresh. 

The  fraction  200° -300°  consists  mainly  of  diphenylmethane 
(see  51,  P-  57)- 

Triphenylmethane  crystallizes  iu  rhombic  crystals,  which  melt 
at  92°.  It  boils  at  358°-359°.  It  is  easily  soluble  in  ether,  chlo- 
roform, and  hot  alcohol,  difficultly  soluble  in  cold  alcohol. 

If  a  little  of  the  hydrocarbon  is  dissolved  in  cold  fuming  nitric 
acid,  and  the  solution  poured  into  water,  tfinitrotriphenylmethane 
is  obtained.  This  may  be  reduced  to  the  amino  compound  by 
zinc  dust  and  glacial  acetic  acid.  The  amine  may  be  precipitated 
from  the  filtered  and  diluted  solution  by  ammonia.  If  the  amine 
is  heated  carefully  on  platinum  foil,  with  a  drop  of  concentrated 
hydrochloric  acid,  the  red  color  of  the  chloride  of  pararosaniiine 
will  be  noticed. 

17.  Preparation  of  a  Hydrocarbon  by  the  Removal  of  a  Hal- 

1  Aluminium  chloride  may  be  prepared  from  aluminium  turnings  and  dry  hydro- 
chloric acid  gas.  (Stockhausen  and  Gattermann,  Ber.,  25,  3521;  Escales,  Ibid,  30,  1314.) 
Gomberg  advises  the  use  of  chloriue,  (Ber.,  33,  3146). 


60  ORGANIC   CHEMISTRY 

ogen  atom  by  Zinc, — Triphenylmethyl  and  triphenylmethyl  per- 

C6H6X 
oxide,  C6H6-C  and  (C6H5)3C— O-O-C(C6H5)8. 

C.H/ 

Literature — Preparation  of  triphenylmethyl  and  triphenylmethyl  per- 
oxide, Gomberg:  J.  Am.  Chem.  Soc.,  22,  757;  Ber.,  33,  3150;  35,  1822; 
Schmidlin:  Ber.,  41,  423;  Preparation  of  triphenylchlormethane,  Gomberg: 
J.  Am.  Chem.  Soc.,  22,  752 ;  Norris  and  Sanders :  Am.  Ch.  J.,  25,  54 ;  Con- 
stitution of  triphenylmethyl,  Gomberg:  Ber.,  39  3^745  4°>  1847;  Gomberg 
and  Cone :  Ann.,  37°,  142 ;  Tschitschibabin :  Ber.,  37,  4709  5  38,  771 ;  4°, 
367,  3965;  41*  2421;  Baeyer:  Ber.,  40,  3oS^iJ>chmidlin :  Ber.,  41,  2471; 
Relation  between  color  and  constitution*  *Curtiss :  J.  Am.  Chem.  Soc.,  32, 
795;  Halochromie,  Baeyer:  Ber.,  35>  1189. 

2  grams  triphenylchlormethajle. 

3  grams  powderecl  zinc. 
10  cc.  benzene. 

Put  in  a  dry  test-tube  2  grams  of  triphenylchlormethane,  3 
grams  of  powdered  zinc  and  15  cc.  of  dry  benzene.  Seal  the 
tube  in  the  blast  and  shake  at  intervals  for  a  day  or  two.  A 
dark  colored  oil  will  collect  in  the  bottom  of  the  tube  as  the 
reaction  progresses.  This  oil  is  a  double  salt  of  triphenylchlor- 
methane and  zinc  chloride.  Test  one  portion  of  the  solution 
with  a  solution  of  iodine  in  benzene  to  show  the  unsaturated 
character  of  the  triphenylmethyl.  Shake  another  portion  of 
the  solution  with  air  and  note  the  formation  of  triphenylmethyl 
peroxide. 

Triphenylmethyl  has  aroused  very  great  interest  and  been  the 
occasion  of  a  very  large  amount  of  work  on  the  part  of  chemists, 
not  only  because  in  some  of  its  forms  it  seems  to  have  a  trivalent 
carbon  atom,  but  also  because  of  the  bearing  which  many  of  the 
facts  discovered  in  connection  with  it  have  upon  the  question 
of  the  relation  between  color  and  chemical  constitution. 

18.  Preparation  of  a  Hydrocarbon  by  Reduction  with  Zinc 
Dust. — Anthracene,  C14H10. 

Literature — Preparation  from  coal  tar,  Dumas,  Laurent:  Ann.,  5» 
10;  From  toluene,  benzene  and  ethylene  at  a  high  temperature,  Berthelot: 
Ann.,  142,  254 ;  Behr,  van  Dorp :  Ber.,  6,  754 ;  By  Friedel  and  Crafts,  reac- 


HYDROCARBONS  6 1 

tion,  Perkin,  Hodgkinson :  J.  Chem.  Soc.,  37>  726;  From  o-bromobenzyl- 
bromide.  The  paper  contains  a  list  of  syntheses  of  anthracene,  Jackson: 
Am.  Chem.  J.,  2,  384;  By  distilling  alizarin  with  zinc  dust,  Graebe, 
Liebermann :  Ann.  Supl,  7»  297 ;  Baeyer :  Ann.,  140*  295 ;  Graebe  and 
Uebermann:  Ber.,  x,  49. 

1  gram  alizarin. 
Zinc  dust. 

Fill  a  combustion  tube  as  follows :  Put  near  one  end  a  loose 
plug  of  asbestos,  then  5  cm.  of  zinc  dust,  then  a  mixture  of 
one  gram  of  alizarin,  with  30  grams  of  zinc  dust,  then  about  30 
cm.  of  a  mixture  of  zinc  dust  with  about  ^  its  weight  of  asbestos, 
then  a  plug  of  asbestos  loosely  packed.  Rap  the  tube  on  the 
table  to  give  a  quite  free  channel  above  the  zinc  dust,  lay  the 
tube  in  the  combustion  furnace,  and  pass  hydrogen  from  the  end 
first  filled  till  the  air  is  expelled.  Heat  the  mixture  of  asbestos 
and  zinc  to  bright  redness,  slowly,  beginning  at  the  rear  end, 
continuing  a  slow  current  of  hydrogen.  Crystallize  the  anthra- 
cene, which  sublimes  to  the  front,  cooler  part  of  the  tube,  from 
benzene  or  toluene,  and  determine  its  melting-point.  Also  oxidize 
a  part  of  it  with  chromic  anhydride  in  glacial  acetic  acid,  and 
determine  the  melting-point  of  the  anthraquinone  (see  42,  p. 
103). 

Anthracene  melts  at  216°  and  boils  at  351°. 

This  method  of  preparing  anthracene  is  of  great  historical  sig- 
nificance, as  it  led  Graebe  and  Liebermann  to  the  discovery  of  the 
character  of  alizarin,  and  so,  indirectly,  led  to  its  synthetical 
preparation. 

19.  Zinc  Ethyl, 

Literature — Frankland:  Ann.,  95,  28;  Beilstein,  Rieth:  Ibid,  123,  245; 
126,  248;  Rathke:  Ibid,  152,  220;  Gladstone,  Tribe:  Ber.,  6,  200;  J.  Chem. 
Soc.,  35,  569;  Kaulfuss:  Ber.,  20,  3104;  Haase:  Ibid,  26,  1053;  Arthur 
Lachman:  Am.  Chem.  J.,  19,  410. 

18  grams  powdered  zinc. 

2  grams  reduced  copper. 
20  grams  ethyl  iodide. 


62  ORGANIC    CHEMISTRY 

Put  in  a  50  cc.  round-bottomed  flask  18  grams  of  powdered 
zinc,1  and  2  grams  of  copper  powder,  obtained  by  reducing  fine 
copper  oxide  in  hydrogen  at  a  low  temperature.  Close  the  flask 
with  a  cork  having  a  small  glass  tube  through  it.  Heat  gently 
over  a  free  flame,  turning  all  the  time  till  the  mass  becomes  gray 
and  loses  its  luster,  but  not  till  there  is  any  sign  of  fusion.  Seal) 
the  glass  tube,  and  allow  to  cool. 

Bend  a  glass  tube,  of  such  size  and  length  as  to  replace  the 
inner  tube  of  a  small  Liebig  condenser,  at  an  angle  of  135°  near 
the  end.  Insert  the  tube  in  the  mantle  of  the  condenser,  clamp 
the  latter  at  an  angle  of  45°  with  the  horizontal,  and  connect  the 
flask  containing  the  zinc-copper  couple  to  the  lower  end  of  the 
bent  tube,  with  a  tightly  fitting  cork.  Pour  in  through  the  con- 
denser 20  grams  of  ethyl  iodide.  Place  a  test-tube,  large  enough 
to  allow  a  small  glass  tube  to  pass  into  it  beside  the  condenser 
tube,  over  the  upper  end  of  the  condenser,  nearly  closing  the 
mouth  of  the  test-tube  with  a  cork  ring  or  with  paper.  Pass  into 
the  test-tube  a  slow  current  of  carbon  dioxide,  and  heat  the  flask 
containing  the  ethyl  iodide  and  zinc-copper  couple  on  the  water- 
bath  as  long  as  ethyl  iodide  continues  to  distil  and  run  back,  us- 
ually only  a  short  time.  Then  turn  the  condenser  in  such  a  way  that 
the  main  tube  of  the  condenser  slants  downward,  and  distil  off  the 
zinc  ethyl  carefully  with  a  free  flame,  continuing  the  current  of 
carbon  dioxide  through  the  test-tube. 

By  heating  on  the  water-bath,  the  ethyl  iodide  reacts  with  the 

zinc,  forming  ethyl  zinc  iodide,  Zn<^     .     On  heating  to  a  higher 

temperature,  zinc  ethyl  is  formed. 

/C2H5 

+  ZnI2. 


On  account  of  its  spontaneous  inflammability  on  coming  to  the 
air,  very  great  care  must  be  exercised  in  working  with  zinc 

1  Baker  and  Adamson's  zinc,  powdered  to  pass  a  30  mesh  sieve,  answers  well  for  this 
purpose.  Arthur  L,achman  (loc.  cit.)  prepares  a  zinc-copper  couple  by  mixing  zinc  dust 
with  one-  eighth  of  its  weight  of  fine  copper  oxide  and  reducing  in  a  current  of  hydrogen 
at  a  dull  red  heat. 


HYDROCARBONS  63 

ethyl,  and  it  must  be  kept  in  sealed  tubes,  and  in  a  fire-proof  case. 
Small  bulbs  can  be  filled  with  the  substance  by  preparing  them 
with  a  small  capillary  tube  on  both  sides,  filling  them  with  carbon 
dioxide,  drawing  the  zinc  ethyl  up  into  the  bulb,  (if  drawn  by 
suction  with  the  mouth  a  large  bulb  of  some  sort  should  be 
interposed),  and  sealing  the  tube  above  the  bulb  with  a  blow- 
pipe. 

Zinc  ethyl  boils  at  118°,  and  has  a  specific  gravity  of  1.182 
at  1 8°.  It  takes  fire  spontaneously  in  the  air,  or  in  chlorine,  and 
decomposes  violently  with  water,  giving  zinc  hydroxide  and 
ethane. 

Zinc  ethyl  is  introduced  here  because  it  has  frequently  been 
used  for  the  preparation  of  hydrocarbons.  It  was  formerly  used 
for  a  variety  of  syntheses  but  nearly  everything  which  has  been 
accomplished  by  its  use  is  now  more  conveniently  effected  by  other 
means.  The  Barbier-Grignard  reaction  (p.  65)  especially,,  has 
replaced  it  for  many  purposes. 


Chapter  IV 


ALCOHOLS  AND  PHENOLS 

Alcohols  are  prepared  from  the  halogen   derivatives   of  hy- 
drocarbons, by  treatment  with  water,  potassium  carbonate  and 
water,  silver  oxide  and  water,  or  potassium  or  silver  acetate, 
followed   by  saponification   of  the   acetic   ester   of  the   alcohol, 
which  is  formed.     The  iodides  react  more  readily  than  other 
halogen  derivatives,  but  bromides  are  often  used. 
2RI  +  K2CO3  +  H2O  .=  2ROH  +  2KI  +  CO2. 
RI  +  AgC2H302  =  R—  O—  CaH30  +  Agl. 
RO  —  C2H3O  +  KOH  =  R  —  OH  +  KC2H3O2. 

From  unsaturated  hydrocarbons  alcohols  can  be  obtained  by 
dissolving  them  in  concentrated  sulphuric  acid,  diluting,  and 
distilling.  The  method  gives  secondary  and  tertiary  alcohols 
in  cases  where  their  formation  is  possible. 

C,,H2W  +  H2S04  -  CWH2M  +  2HSCV 
CMH2W  +  .HSO,  -f  H20  =  CttH2W  +  XOH  +  H2SO4. 

Aldehydes  may  be  reduced  to  primary  alcohols,  and  ketones 
to  secondary  alcohols.  The  reducing  agents  most  often  used  are 
sodium  amalgam  in  aqueous  solutions,  sodium  in  alcoholic  or 
moist  ethereal  solutions,  or  zinc  dust  and  glacial  acetic  acid. 
The  last  method  gives  an  acetate,  which  requires  saponificalion. 

Amines  may  be  converted  into  alcohols  by  the  action  of 
nitrous  acid  in  aqueous  solutions.  In  the  aromatic  series  a  diazo 
compound  is  first  formed.  In  the  aliphatic  series,  and  especially 
in  cyclic  compounds,  unsaturated  hydrocarbons  are  also  formed, 
and  interfere  seriously  with  the  yield. 

RNH2  +  HN02  =  ROH  +  N2  +   H2. 

/H 

R<  +  HN02  =  R"  -f  N2  -f  2H2O. 

XNH2 

In  the  aromatic  series   sulphonic  acids,   and   in   many  cases 


ALCOHOLS  AND  PHENOLS  65 

halogen  derivatives,  may  be  converted  into  phenols  by  fusion 
with  potassium  hydroxide.  The  reaction  is  accompanied,  in 
some  cases,  by  a  rearrangement,  which  interferes  with  its  re- 
liability for  the  determination  of  structure. 

RSO2OH  +  2KOH  =  ROH  +  K2SO3  +  H2O. 
Glycols,  that  is,   alcohols  having  two  hydroxyl  groups  com- 
bined with  adjacent  carbon  atoms,  may  be  prepared,  in   some 
cases,  by  oxidizing  olefires  with  a  cold  solution  of  potassium 
permanganate. 

R  —  CH  R  —  CHOI} 

+  O  +  H,0  =  \ 

R  -  CH  R  —  CHOH 

This  reaction  is  of  greater  importance  for  the  preparation  of 
dihydroxy  acids  than  for  the  preparation  of  glycols,  however. 
(See  Fittig:  Ber.,  27,  2670.) 

Many  aromatic  aldehydes,  on  treatment  with  potassium  hy- 
droxide and  water,  are  converted  into  a  mixture  of  the  potassium 
salt  of  the  corresponding  acid,  and  the  corresponding  alcohol. 
2RCHO  +  KOH  =  RCH2OH  +  RCO2K. 

Barbier1  and  Grignard  discovered  in  1899-1900  that  the  organo- 
magnesium  halides  of  the  type  R — Mg — Br(I)  formed 
by  the  action  of  halogen  compounds  on  magnesium  in  dry  ether 
may  be  used  for  a  great  variety  of  syntheses.  Contrary  to  its 
conduct  in  most  other  cases  the  halogen  of  aromatic  as  well  as  of 
aliphatic  compounds  may  be  replaced  by  reactions  carried  out 
at  or  below  the  boiling-point  of  ether  by  this  method  and  it  has 
practically  replaced  all  reactions  for  which  zinc  alkyl  compounds 
were  formerly  used.  The  most  important  applications  of  the 
Bajbier-Grignard  syntheses  are  the  following: 

i.  Preparation  of  hydrocarbons,  Grignard:  Compt.  rend.,  130, 
1322. 

R— MgBr  +  HOH  =  RH  +  Mg(OH)Br. 

R— MgBr  +  R'OH  =  RH  +  R'.OMgBr. 

The  second  reaction  may  sometimes  be  used  for  the  detection 
and  even  for  the  determination  of  hydroxyl  in  organic  com- 

1  The  reaction  has  been  generally  know  as  the  Grienard  reaction  but  it  seems  to  have 
been  first  used  bv  Barbier  (Comn.  rend.,  128,  110,  (1899)),  and  Grignard  undertook  the 
study  of  the  reaction  at  the  suggestion  of  Barbier. 


66  ORGANIC   CHEMISTRY 

pounds   by   measuring  the   amount  of  methane   liberated   when 
methyl  magnesium  iodide  acts  upon  the  compound.     Tschugaeff: 
Ber.,  35,  3912  ;  Zerewitinoff  :  Ber.,  40,  2023. 
2.  Preparation  of  alcohols. 

a.  By  the  successive  action  of  oxygen  and  water  on  the  or- 
ganomagnesium   halide.     Thus    pinene    chlorhydrate    gives    bor- 
neol: 

C10H17MgCl  +  O  =  C10H17OMgCl. 

C10H1TOMgCl  +  H20  =  C10H17OH  +  Mg(OH)Cl. 

b.  By  the  action  of  the  organomagnesium  halide  on  a  ketone 
or  an   aldehyde, 

Rv  Rv       /CH3 

>CO  +  CH3MgI  =       >C< 
R/  R/      X)MgI 


, 

-I-  H20  -      >C  +  Mg(OH)I 

R/         OMgI  R/ 


,0 
or  R  —  C<      -f  CH3MgI  =  R—  C—  OMgl  ^>  R  —  CHOHCH.. 

XH  \H 

Ketones   give   tertiary   alcohols,   aldehydes   give   secondary. 
c.  By  the  action  of  the  organomagnesium  halide  on  an  ester, 
giving  a  tertiary  alcohol. 

O 

// 
C6H5C—  OCH3  +  C6H5MgBr 

xOMgBr 

=  C6H4-C6H5 

SXOCHS 


C6H5  -  C-C6H5       +  C6H5MgBr 

\OCH, 

.OMgBr 

=  C6H5  —  C-C6HB  +  CHsOMgBr 
XQ  H 

—  (C6H5)3COH  -h  Mg(OH)Br. 


ALCOHOLS   AND    PHENOLS  67 

d.  From  acid  chlorides, 

/OMgl 
CH3COC1  +  CH3MgI  =  CH3  —  C—  CHS 


X)MgI  x 

CH3—  C—  CH3      +  CH3MgI  =  CH3  -  C-CH3  +  MgClI 

\C1  ^CH, 

—  (CH3)3COH  +  Mg(OH)I. 

3.  Preparation   of   aldehydes   from   orthoformic   ester.     Grig- 
nard:  Compt.  rend.,  138,  92;  Gattermann  and  MafTezzoli:  Ber., 
36,  4152. 

HC(OC2H5)3  +  CcH5MgBr  =  CCH5CH(OC2H5)2 

+  C2H5OMgBr. 

C6H5  —  CH(OC2H5)2  +  HC1  +  H20  =  C6H5CHO  +  HC1 

+  2C2H5OH. 

4.  Preparation  of  ketones  from  a  nitrile  and  an  organomagne- 
sium  halide.     Blaise  :  Comp.  rend.,  132,  38. 

C6H5CN  +  C2H5MgI  ==  C6Hr-  C  —  C2H5 

II 
N—  Mgl 

C6Hf  -  C  -  C2H5  C6H5  -  C  -  C2H5 

II  +  H20  =  +  Mg(OH)I 

NMgl  NH 

C6H5  —  C  —  C2H5  +  H2O  =  C6H5COC,H5  +  NHS. 

li 
NH 

The  literature  of  the  Barbier-Grignard  synthesis  is  very  volu- 
minous. The  following  authors  have  prepared  good  sr.mma- 
ries;  Tscheiinzeff  :  Ber.,  37,  2081;  C.  E.  Waters:  Am.  Chem.  J.. 
33»  304;  Alex,  McKenzie.  British  Assoc.  Report,  Section  B, 
Leicester,  1907.  See  also  Chem.  Centralbl.,  1901,  II,  62,  and 
Schmidt,  Ahren's  Sammlung,  10,  67,  and  13,  357,  complete 
bibliography. 

20.  Preparation  of  Absolute  Ethyl  Alcohol,  CH3CH2OH. 

Literature.  —  Use  of  lime,  Soubeiran  :  Ann.,  3°»  356  ;  Erlenmeyer  :  Ann., 
160,  249;  Warren:  J.  Am.  Chem.  Soc.,  32,  698;  Use  of  barium  oxide  to 
indicate  the  end,  Berthelot  :  Jahresb..  1862,  392;  Use  of  calcium  carbide, 


68 


ORGANIC   CHEMISTRY 


Yvon:  Compt.  rend.,  125,  1181;  Ostermayer:  Chem.  Centralbl.,  '98,  I,  658; 
Use  of  benzene,  Young:  Chem.  Centralbl.,  '03,  II,  869;  Boiling-point  curve 
for  ethyl  alcohol  and  water,  Noyes  and  Warf el :  J.  Am.  Chem.  Soc.,  23> 
463;  Alcoholometric  table,  Morley:  J.  Am.  Chem.  Soc.,  26,  1186. 

I  liter  of  alcohol. 
300  grams  lime. 

Distillate   from  the  above   mixture. 
200  grams  lime, 
i  gram  barium  oxide. 

Put  300  grams  of  good  lime  in  -a  1,500  cc.  flask.     Add  i  liter 
of  ordinary  alcohol  and  allow  to  stand  over  night.     Place  the 


Fig.  24. 

flask  on  a  water-bath,  connect  with  an  upright  condenser  (Fig. 
24)  and  boil  gently  for  two  hours.  Then  connect  with  the  con- 
denser by  means  of  a  bent  tube  and  distil  away  the  alcohol, 
collecting  it  in  a  dry  flask.  Add  to  the  distillate  200  grams  of 
lime  and  about  one  gram  of  barium  oxide.  Allow  to  stand 
over  night  and  then  connect  with  the  upright  condenser  as  be- 


ALCOHOLS   AND    PHENOLS  69 

fore  and  boil  for  two  hours  or  until  the  barium  oxide  dissolves 
imparting  a  yellow  color  to  the  alcohol.  Distil  away  the  alcohol 
as  before  but  collect  in  a  distilling  bulb  connected  to  the  lower 
end  of  the  condenser  with  a  tightly  fitting  cork  and  having  a 
calcium  chloride  tube  connected  to  its  side  tube  to  prevent  moist 
air  from  entering  the  bulb.  Determine  the  specific  gravity  and 
strength  of  the  alcohol  (p.  32). 

The  boiling-point  of  absolute  alcohol  is  78.3°  (Ramsey  and 
Young:  J.  Chem.  Soc.,  47,  640).  Its  specific  gravity  at  20°  is 
0.78932.  It  will  not  cause  anhydrous  copper  sulphate  to  turn 
blue  even  on  long  standing  with  it  and  it  will  not  evolve  acety- 
lene with  calcium  carbide. 

If  turnings  of  metallic  calcium  are  available,  the  last  portions 
of  water  may  be  removed  more  rapidly  by  warming  the  alcohol 
with  these. 

Prepare  some  sodium  ethylate  by  dissolving  a  piece  of  sodium 
the  size  of  a  pea  in  i  cc.  of  absolute  alcohol  in  a  tCbt-ttibe.  If 
the  alcohol  is  absolute  and  the  solution  sufficiently  concentrated, 
it  will  solidify  on  cooling.  Notice  also  that  such  a  solution 
darkens  rapidly  on  exposure  to  the  air  while  a  solution  of  so- 
dium hydroxide  in  pure  alcohol  darkens  slowly,  if  at  all. 

21.  Preparation  of  an  Unsatnrated  Alcohol. — Allyl  alcohol, 
CH2  =  CH  --  CH2OH.  (i.3-propenol). 

Literature — Berthelot  and  de  Lucca:  Ann,.ioo,  359;  Cahours  and  Hof- 
mann :  Ibid,  102,  285 ;  Aronheim :  Ber.,  7>  1381 ;  Tollens,  Henninger :  Ann., 
156,  134,  142;  Tollens:  Ibid,  167,  222;  Romburgh :  Jahresb.,  1881,  508; 
Bigot:  Ann.  chim.  phys.,  [6],  23*  464. 

200  grams  glycerol. 

50  grams  crystallized  oxalic  acid. 

0.25  gram  ammonium  chloride. 

In  a  300  cc.  distilling  bulb  put  200  grams  of  glycerol,  50  grams 
of  crystallized  oxalic  acid,  and  %.  gram  of  ammonium  chloride, 
the  last  being  added  to  decompose  any  alkali  salts  present,  which 
would  interfere  with  the  reaction.  Insert  a  thermometer,  im- 
mersed in  the  liquid,  and  connect  with  a  condenser.  Heat  gent- 
ly so  that  the  temperature  rises  slowly.  The  portion  distilling 


7O  ORGANIC   CHEMISTRY 

• 

below  195°  consists  mainly  of  dilute  formic  acid  (see  45,  p.  U5)> 
and  may  be  converted  into  the  lead  salt  by  boiling  with  lead  car- 
bonate. Collect  by  itself  the  portion  coming  over  from  195° 
to  240°.  When  the  latter  temperature  is  reached,  cool,  add  30 
grams  of  oxalic  acid  and  distil  as  before. 

Unite  the  distillates  (i95°-24O°)  and  distil,  collecting  the  por- 
tion boiling  below  105°.  Add  dry  potassium  carbonate  till  the 
allyl  alcohol  separates  above,  separate  and  add  10  per  cent,  of  its 
weight  of  powdered  caustic  potash,  and  allow  the  mixture  to 
stand  for  some  time,  until  the  odor  of  acrolein  has  disappeared, 
separate  and  distil,  collecting  the  portion  boiling  at  9O°-96°. 
In  order  to  remove  the  last  traces  of  water,  it  is  necessary  to  dis- 
til again,  after  standing  for  some  time  with  lime  or  barium  oxide. 
Yield  12  to  15  grams. 

Allyl  alcohol  boils  at  96.6°,  and  has  a  specific  gravity  of 
0-8573,  at  15°.  When  dilute  allyl  alcohol  is  treated  with  bromine 
dissolved  in  a  solution  of  potassium  bromide,  the  dibromide, 
CH2BrCHBrCH2OH,  is  formed,  and  the  reaction  may  be  used 
for  quantitative  determinations. 

22.  Preparation  of  a  Phenol  by  the  Decomposition  of  an  Amine 

/CH,  (i) 
through  the  Diazonium  Compound.— Paracresol,  C6H/ 

XOH    (4) 
(/>-Methyl  phenol.) 

Literature — Stiideler:  Ann.,  77,  17;  Salkowski:  Ber.,  12,  1440;  Griess: 
Jahresb.,  1866,  458;  Korner:  Ztschr.  Chem.,  1868,  326;  Wurtz :  Ann.,  144, 
129;  Fittig  and  Kiesow:  156,  258;  Oudemans:  Ibid,  170,  259;  Southwarth: 
Ibid,  1 68,  271 ;  Pinette :  Ibid,  243,  43. 

20   grams   paratoluidine. 

600  cc.  water. 

20  cc.  concentrated  sulphuric  acid. 

15   grams   sodium  nitrite. 
75   cc.    water. 
2  grams  urea. 

» 

30  cc.  sodium  hydroxide  (3  cc.  =  I  gram). 
10  cc.  concentrated  sulphuric  acid. 
30  cc.  water. 


ALCOHOLS    AND    PHENOLS  /I 

In  a  one  liter  flask  put  20  grams  of  paratoluidine,  600  cc.  of 
water,  and  20  cc.  of  concentrated  sulphuric  acid.  Heat  till  dis- 
solved. Cool  to  20°  or  below,  and  add  slowly,  with  shaking, 
a  solution  of  15  grams  of  sodium  nitrite,  in  75  cc.  of  water, 
keeping  the  temperature  below  20°.  Allow  to  stand  for  a  short 
time,  add  2  grams  of  urea,  connect  with  a  condenser,  and  distil 
over  the  paracresol  with  water  vapor.  For  this  purpose  the  flask 
is  fitted  as  shown  in  Fig.  25  with  a  stopper  bearing  two  glass 


Fig.  25. 

tubes.  One  of  these  should  reach  nearly  to  the  bottom  of  the 
flask  or  distilling  bulb  and  should  be  bent  to  one  side  in  such 
a  manner  that  the  escaping  steam  will  give  a  rotary  motion  to 
the  liquid.  The  fle.sk  should  be  inclined  so  that  the  steam  w:ll 
throw  the  liquid  upward  toward  the  side  of  the  flask  and  not 
into  its  neck.  The  second  tube  connects  with  the  condenser. 
The  steam  is  best  generated  in  a  two  quart  can  of  tin,  copper 
or  galvanized  iron.  The  stopper  of  the  can  bears  two  tubes,  one 
about  a  meter  long  reaching  nearly  to  the  bottom  of  the  can, 
the  other  a  short  bent  tube  to  carry  away  the  steam.  The  latter 
is  connected  with  the  longer  tube  in  the  flask  by  means  of  a 
rubber  tube.1  Continue  the  distillation  till  the  distillate  gives 

o 

no  turbidity  with  bromine  water.  Add  to  the  distillate  30  cc. 
of  a  strong  solution  of  caustic  soda  and  a  little  bone-black,  and 

1  For  a   simple  apparatus   for  steam   distillation,    using  a  reversed  condenser,  see 
Mathews,  J.  Chein.  Soc.,  71,  318. 


72  ORGANIC   CHEMISTRY 

concentrate  rapidly  to  about  75  cc.  by  boiling  in  a  large  lip 
beaker,  covered  with  a  watch-glass,  to  prevent  oxidation.  Filter 
into  a  beaker  containing  10  cc.  of  concentrated  sulphuric  acid 
diluted  with  30  cc.  of  water.  Cool,  and'  extract  the  cresol  with 
ether,  extracting  three  or  four  times.  Dry  the  solution  for  a 
few  minutes  with  calcium  chloride,  pour  off,  distil  the  ether 
from  a  water-bath,  dry  the  residue  in  vacuo  over  sulphuric  acid, 
and  distil.  Yield  15  to  16  grams. 

The  urea  is  added  to  destroy  the  excess  of  nitrous  acid,  which, 
if  allowed  to  remain,  would  interfere  seriously  with  the  yield. 

Paracresol  crystallizes  in  prisms  which  melt  at  36°.  It  boils 
at  201.8°,  and  has  a  specific  gravity  of  0.9962  at  65.6°.  It  is 
slightly  soluble  in  water.  Its  aqueous  solution  gives  a  blue  color 
with  ferric  chloride.  There  is  usually  difficulty  in  getting  the 
cresol  to  solidify.  In  that  case  a  drop  may  be  put  in  a  dry 
test-tube,  placed  in  some  ether  in  a  small  beaker.  By  blowing 
air  through  the  ether  the  temperature  can  be  lowered  to  o°  or 
below.  When  a  crystal  of  cresol  obtained  in  this  way  is  added  to 
the  rest,  the  whole  will  solidify. 

23.  Preparation  of  an  Alcohol  of  the  Aromatic  Series  by 
Treatment  of  an  Aldehyde  with  Caustic  Potash. — Benzyl  alcohol, 
C6H5CH2OH  (phenmethylol). 

Literature — Kraut:  Ann.,i52,  129;  Busse :  Ber.,  9,  830;  Cannizzaro : 
Ann.,  88,  129;  96,  246;  Herrmann:  Ibid,  132,  76;  Lauth,  Grimaux:  Ibid, 
i43>  81;  Niederest:  Ibid,  196,  353;  Kachler:  Ber.,  2,  514;  R.  Meyer: 
Ibid,  i4»  2394;  Graebe:  Ibid,  8,  1055. 

30   grams   benzaldehyde. 

27  grams  potassium  hydroxide. 

25  cc.  water. 

Dissolve  27  grams  of  caustic  potash  in  25  cc.  of  water,  add 
the  solution  to  30  grams  of  benzaldehyde,  and  shake  till  an 
emulsion  is  formed.  Allow  the  mixture  to  stand  for  24  hours. 
Add  enough  water  to  dissolve  the  potassium  benzoate,  and  ex- 
tract with  ether.  Distil  off  the  ether,  dry  under  diminished  pres- 
sure with  a  capillary  (see  75,  p.  171  and  138),  and  distil  with  an 
air  condensing  tube.  From  the  alkaline  solution  the  benzoic  acid 


ALCOHOLS  AND  PHENOLS  73 

. 

may  be  precipitated  and  purified  by  recrystallizing  from  hot 
water.  Yield  14  to  15  grams,  if  the  benzaldehyde  used  is  free 
from  benzoic  acid. 

Benzyl  alcohol  boils  at  204.7°,  and  has  a  specific  gravity  of 
1.0507  at  15.4°.  It  dissolves  in  25  parts  of  water  at  17°.  It 
combines  with  calcium  chloride,  and  cannot  be  dried  by  that 
agent. 

24.  Preparation  of  an  Alcohol  by  the  Reduction  of  a  Ketone. — 

Phenyl  methyl  carbinol,          ' \CHOH,  phenethylol  (i). 

CH/ 

Literature — Radziszewski :  Ber.,  7,  141 ;  Berthelot :  Ztschr.  Chem.,  1868, 
589;  Emmerling,  Engler:  Ber.,  4,  147;  6,  1006. 

10   grams   acetophenone. 

100  cc.   ether. 

30  cc.  water. 

8-10  grams  sodium. 

Put  in  a  200  cc.  flask  10  grams  of  acetophenone,1  30  cc.  of 
water,  and  100  cc.  of  ether.  Add  sodium  in  small  pieces,  shaking 
gently,  and  cooling  the  flask  with  water,  till  the  ethereal  solu- 
tion no  longer  gives  a  turbidity  when  a  drop  of  it  is  put  in  a  test- 
tube  with  a  dilute  solution  of  phenyl  hydrazine  acetate  (see 
p.  89).  8-10  grams  of  sodium  will  usually  be  required.  To- 
ward the  close  more  water  may  be  added,  if  the  solution  of  the 
sodium  takes  place  too  slowly.  Separate  the  ethereal  solution, 
distil  off  the  ether,  dry  the  residue  in  vacuo  over  sulphuric  acid, 
or  by  heating  on  a  water-bath  under  diminished  pressure  with  a 
capillary  (pp.  171  and  138),  and  distil.  Yield  6  to  7  grams.  The 
yield  is  diminished  by  the  formation  of  the  pinacone. 

>C  —  C 

CH/   |          | 

OH    OH 

1  This  may  be  prepared  exactly  as  directed  for  benzophenone  (p.  101),  using  12  grams 
of  acetyl  chloride  in  place  of  20  grams  of  benzo}-!  chloride.  The  yield  is  about  12  grams 
of  acetophenone.  It  melts  at  20.5°  and  boils  at  202°.  Acetophenone  may  also  be  prepared 
by  bringing  together  equivalent  amounts  of  benzoic  acid  and  acetic  acid  with  some 
water,  and  a  little  more  than  the  equivalent  amount  of  calcium  carbonate,  evaporating  to 
drvness  and  distilling  the  residue  from  a  retort  or  flask. 


74  ORGANIC   CHEMISTRY 

* 

Thenyl-methyl-carbinol  boils  at  202°  -204°,  and  has  a  specific 
gravity  of  1.013. 

25.  Preparation  of  a  Tertiary  Alcohol  from  an  Ester  by  Means 
of  a  Magnesium  Organic  Compound.—  Barbier  and  Grignard's 


Synthesis,  Triphenyl  Carbinol.     C6H5  —  C—  O—  H. 

C.H/ 

Literature  __  Preparation  from  triphenyl  methane,  Hemilian  :  Ber.,  7» 
1206;  By  Barbier  ad  Grignard's  reaction,  Ullmann  and  Miinzhuber:  Ber., 
36,  404;  Grignard:  Compt.  rend.,  130,  1322  (alcohols,  hydrocarbons);  132, 
853  (Organometallic  compounds  of  Mg.)  ;  133,  1182  (Compounds  from 
bromobenzene  and  esters  of  ketones)  ;  Centralblatt,  i9OI>  II,  622  (acids 
from  alkyl  halides  and  carbon  dioxide,  secondary  alcohols  from  alde- 
hydes and  tertiary  alcohols  from  ketones  and  from  esters)  ;  W.  Tschelin- 
zeff:  Ber.,  37»  2081  (List  of  reactions);  C.  E.  Waters:  Am.  Chem.  J., 
33»  304  (Report  and  bibliography);  Alex  McKenzie:  British  Associa- 
tion Reports,  Section  B.  Leicester,  1907. 

4.8  grams  magnesium  ribbon. 

100  cc.  dry  ether. 

40  grams  bromobenzene. 

30  grams  ethyl  benzoate. 

10  cc.  sulphuric  acid   (1:1). 

Take  200  cc.  of  ether  which  has  been  dried  by  distillation 
over  calcium  chloride  (p.  175)  add  15  grams  of  phosphorus 
pentoxide  and  allow  to  stand  over  night.  Pour  into  a  distilling 
bulb  containing  10  grams  of  phosphorus  pentoxide,  boil  with 
an  upright  condenser  and  with  the  side  tube  closed,  for  an  hour, 
then  distil,  collecting  in  a  dry  distilling  bulb  attached  tightly  to 
the  lower  end  of  the  condenser  with  a  cork  and  having  the 
side  neck  directed  upward  and  protected  from  moisture  by  means 
of  a  calcium  chloride  tube.  Discard,  or  use  for  some  other  pur- 
pose the  first  10  cc.  of  ether  collected,  also  leave  about  15  cc.  of 
ether  undistilled  in  the  flask  containing  the  phosphorus  pent- 
oxide. 

Put  in  a  200  cc.  flask  4.8  grams  of  clean  magnesium  ribbon, 
add  a  crystal  of  iodine  and  100  cc.  of  the  dry  ether,  then  40 
grams  of  bromobenzene.  Cool  with  ice-water,  if  the  reaction  is 


ALCOHOLS  AND  PHENOLS  75 

violent  or,  if  the  reaction  does  not  begin,  warm  gently  on  a  water- 
bath  connecting  the  flask,  in  either  case,  with  an  upright  con- 
denser, the  upper  end  of  which  is  protected  by  a  soda-lime  tube. 
If  magnesium  phenyl  bromide  separates,  add  more  dry  ether  in 
sufficient  amount  to  keep  it  in  solution.  When  the  magnesium 
has  been  dissolved,  cool  and  add  through  the  condenser,  drop- 
ping it  slowly  from  a  dropping  funnel,  30  grams  of  ethyl  ben- 
zoate  which  has  been  allowed  to  stand  for  a  day  with  anhydrous 
sodium  sulphate  and  distilled.  The  ethyl  benzoate  is  weighed, 
of  course,  after  distillation. 

Boil  the  mixture  gently  for  an  hour  with  an  upright  con- 
denser, cool  and  pour  the  mixture  into  a  beaker  containing 
broken  ice  and  10  cc.  of  sulphuric  acid  (1:1  by  volume). 
Separate  the  ethereal  layer  shake  it  three  times  vigorously  with 
20  cc.  of  dilute  sulphuric  acid  (5  per  cent).  Distil  off  the  ether 
from  a  distilling  bulb  and  distil  the  residue  with  steam  (p.  71) 
as  long  as  bromobenzene  or  ethyl  benzoate  passes  over.  Cool, 
filter  off  the  triphenyl  carbinol,  and  wash  and  recrystallize  from 
alcohol.  Yield  15  to  18  grams.  Triphenyl  carbinol  melts  at 
162°.  It  dissolves  in  concentrated  sulphuric  acid  with  an  intense 
yellow  color. 

26.  Preparation  of  a  Diacid  Alcohol  from  a  Halogen  Deriva- 

CH2OH 
tive  of  a  Hydrocarbon. — Ethylene  glycol,    |  (Ethanediol). 

CH2OH 

Literature — Wurtz:  Compt.  rend.,  43,  199,  (1856}  Jeltekow:  Ber.,  6,  558; 
Niederest:  Ann.,  186,  393;  196,  354;  Erlenmeyer:  Ibid,  iQ2»  244;  Stemp- 
newsky:  Ibid,  192,  241;  Wagner:  Ber.,  21^  1234,  3346;  Haworth  and 
W.  H.  Perkin,  Jr.:  J.  Chem.  Soc.,  69,  175. 

1 8.8  grams  ethylene  bromide   (three  times  repeated). 

13.8  grams  potassium  carbonate  (three  times  repeated). 

TOO  cc.  water. 

Put  in  a  200  cc.  flask  18.8  grams  of  ethylene  bromide,  13.8 
grams  of  dry  potassium  carbonate,  and  100  cc.  of  water.  Con- 
nect with  a  reversed  condenser,  and  boil*  gently  till  the  ethylene 
bromide  disappears,  usually  eight  to  ten  hours.  Add  the  same 


76  ORGANIC   CHEMISTRY 

amounts  of  ethylene  bromide  and  potassium  carbonate,  and  boil 
as  before.  Repeat  a  third  time.  The  addition  of  a  few  small 
pieces  of  wood  will  help  to  prevent  bumping.  Some  vinyl  bro- 
mide, CH2  =  CHBr,  escapes  during  the  boiling,  and  can,  if  de- 
sired, be  converted  into  tribromomethane,  by  leading  through  a 
bottle  containing  bromine.  If  large  amounts  of  glycol  are  de- 
sired, the  addition  of  ethylene  bromide  and  potassium  carbonate 
may  be  repeated  six  times  instead  of  three,  but  in  that  case  it  is 
necessary  to  filter  off  the  potassium  bromide,  which  separates,  on 
cooling  the  solution  after  each  boiling. 

Concentrate  the  solution  in  vacuo  over  sulphuric  acid,  pour  off 
from  the  potassium  bromide  which  separates,  wash  the  latter 
with  a  little  absolute  alcohol,  and  submit  the  glycol  to  fractional 
distillation.  Or  the  aqueous  solution  may  be  distilled  at  once, 
best  under  diminished  pressure,  and  the  distillate  used  in  a  new 
preparation,  since  the  glycol  is  quite  volatile  with  water  vapor. 

Ethylene  glycol  is  a  colorless  liquid,  with  a  sweet  taste.  It 
boils  at  197°,  and  solidifies  in  a  freezing  mixture.  It  is  miscible 
in  all  proportions  with  water  and  alcohol,  but  not  with  ether. 

C02H 
Platinum  black  oxidizes  it  to  gly collie  acid,     | 

CH.OH 

27.  Preparation  of  a   Dihydroxy    Compound    from    an    Amine 

/OH  (i). 
through  'the    Quinone.— Hydroquinone,     C6H4<(  (1.4- 

N)H(4). 
Phendiol). 

Literature — Workresenski :  Ann.,  27,  268;  Wohler:  Ibid,  45>  354; 
Nietski:  Ibid,  215,  127;  Ber.,  19,  1467;  Schniter:  Ibid,  20,  2283;  Wohler: 
Ann.,  51,  152;  Strecker:  Ibid,  107,  229;  Salkowski :  Ber.,  7,  1010;  Hlasi- 
wetz:  Ann.,  i75»  67;  Wesclski  and  Schuler:  Ber.,  9»  1160;  Richter:  J. 
prakt.  chem.,  [2],  20,  207,  (1879)  ;  Herrmann:  Ann.,  211,  336;  Ekstrand: 
Ber.,  ii,  713;  Clarke:  Am.  Chem.  J.,  14,  555;  Nef :  Ibid,  12,  483;  Seyda: 
Ber.,  16,  687;  Theory  of  the  preparation,  Willstatter  and  Dorogi:  Ber., 
42,  2147. 


ALCOHOLS  AND  PHENOLS 


77 


10  grams  aniline. 

250  cc.  water. 

80  grams   (44  cc.)   concentrated  sulphuric  acid. 

30  grams  sodium  pyrochromate. 

120  cc.  water. 

Sulphur  dioxide. 

Put  in  a  beaker  10  grams  of  aniline,  250  cc.  of  water,  and 
80  grams  (44  cc.)  of  concentrated  sulphuric  acid.  Put  the  beak- 
er in  ice-water  or  a  freezing  mixture,  and  cool  to  5°.  Stir  the 
solution  by  means  of  a  turbine  or  hot  air  motor,  and  drop  in 
very  slowly  a  solution  of  10  grams  of  sodium  pyrochromate  in 


Fig.  26. 

40  cc.  of  water.  Allow  the  solution  to  stand  in  a  cool  place  over 
night,  and  then  add,  with  stirring  and  cooling,  as  before,  20 
grams  of  the  pyrochromate,  dissolved  in  80  cc.  of  water.  The 
temperature  should  not  rise  above  10°  during  the  addition  of 
the  salt.  If  the  sodium  pyrochromate  can  not  be  had,  very 
finely  powdered  potassium  pyrochromate  may  be  used  instead. 
After  five  or  six  hours,  pass  into  the  solution,  which  now  con- 


ORGANIC   CHEMISTRY 


tains  quinone,  C6H4O2,  a  rapid  current  of  sulphur  dioxide1-  till 
the  solution  smells  very  strongly  of  the  gas.  If  the  odor  of  the 
gas  disappears  after  two  hours,  pass  in  more  of  the  gas  and  al- 
low the  mixture  to  stand  again.  Extract  the  solution  several 
times  with  ether  (see  74,  p.  167),  distil  off  the  ether,  and  crystal- 
lize the  hydroquinone  from  water,  using  a  little  bone-black  to 
decolorize  it,  and  a  little  sulphur  dioxide  to  prevent  oxidation. 
Yield  6  to  8  grams.  The  yield  may  be  increased  by  using  the 
bichromate  at  first  to  form  aniline  black  and  oxidizing  the  latter 
with  lead  peroxide,  Willstatter  and  Dorogi  :  Ber.,  42,  2161. 

Hydroquinone  crystallizes  in  colorless  prisms,  which  melt  at 
169°.  It  is  soluble  in  17  parts  of  water  at  15°. 

28.  Preparation  of  a  Dihydroxyquinone  by  Fusion  of  a  Sul- 
phonic  Acid  with  Sodium  Hydroxide  and  Potassium  Chlorate. 
—  Alizarin, 

H  OH 


H 


\O 


H 


y\co/\/ 

H  H 


H 


( i  .2-Anthraquinonediol ) . 

Literature — Graebe,  Liebermann :  Ann.,  160,  131;  Liebermann:  Ber., 
7,  805;  A.  G.  Perkin,  Hummel:  J.  Chem.  Soc.,  63,  1167;  Liebermann, 
Graebe :  Ann.  SupL,  7,  296 ;  Ber.,  i,  49,  104,  106 ;  3>  359 ;  Perkin :  J.  Chem. 
Soc.,  2,  576,  (1876);  Gerstl:  Ber.,  9,  281;  Liebermann,  Lif  schiitz :  Ber., 
17,  901 ;  Lagodzinski :  Ber.,  28,  1422,  1427. 

10  grams  anthraquinone. 

25  cc.  fuming  sulphuric  acid  (sp.  gr.  1.875  at  25°). 

200  cc.  water. 

50  grams  salt. 

1  This  is  most  easily  generated  by  dropping  concentrated  sulphuric  acid  into  a  40  per 
cent,  solution  of  acid  sodium  sulphite. 


ALCOHOLS    AND    PHENOLS  79 

10  grams   sodium  anthraquinone   sulphonate. 

40  grams  sodium  hydroxide. 

5   grams  water. 

3  grams  potassium  chlorate. 

Put  in  a  small  flask  10  grams  of  anthraquinone,  and  25  cc 
of  fuming  sulphuric  acid  (containing  10  to  12  per  cent,  of  the 
anhydride;  sp.  gr.  1.875  at  25°)-  Cover  with  a  small  watch- 
glass,  and  heat  to  200° -230°  in  an  oil-bath,  raising  the  tempera- 
ture to  this  point  slowly,  for  about  two  hours,  or  till  a  drop  of 
the  solution  separates  little  or  no  anthraquinone  on  dilution  with 
water.  Allow  to  cool,  pour  into  200  cc.  of  water,  filter,  if  nec- 
essary, and  add  50  grams  of  salt,  stir  thoroughly  and  allow 
to  stand  for  some  time,  in  cold  water,  till  the  sodium  anthraqui- 
none sulphonate  separates.  Filter  off,  press,  and  dry  on  porous 
porcelain. 

In  a  nickel  or  iron  crucible  put  40  grams  of  sodium  hydroxide, 
and  5  cc.  of  water,  and  warm  gently  till  the  mass  melts,  then 
stir  in  a  mixture  of  10  grams  of  the  sodium  anthraquinone 
sulphonate,  with  3  grams  of  potassium  chlorate.  The  latter  is 
for  the  purpose  of  oxidizing  to  alizarin  the  hydroxyanthraqui- 
none  which  is  formed  by  fusion  with  the  sodium  hydroxide,  from 
the  monosulphonate.  Heat  gently  and  stir  for  five  to  ten  min- 
utes, and  cool. 

The  transformation  may  also  be  effected  with  advantage  in  an 
autoclave,  or  in  an  iron  tube  (Mannesmann  tube),  having  a 
cap  screwed  on  the  end  which  is  made  tight  with  a  lead  washer. 
In  that  case  use  40  cc.  of  water  instead  of  5  cc.,  and  heat  for 
20  hours  at  170°. 

Dissolve  the  fused  mass  in  hot  water,  filter,  neutralize  the  hot 
solution  with  hydrochloric  acid  (150  cc.,  sp.  gr.  i.n),  filter 
off,  wash,  and  dry  the  precipitated  alizarin.  The  alizarin  may 
be  crystallized  from  alcohol,  glacial  acetic  acid,  or  nitrobenzene. 
It  may  also  be  obtained  in  beautiful  crystals  by  sublimation. 
For  this  purpose  sink  a  porcelain  crucible,  about  5  cm.  in  diam- 
eter, in  a  sand  bath  to  its  edge,  cover  it  with  a  round  filter,  place 
on  this  a  funnel  of  the  same  size  as  the  crucible,  with  the  stem 


8O  ORGANIC   CHEMISTRY 

closed  with  a  rubber  cap,  or  bit  of  rubber  tubing,  with  a  rod  in 
it.  Having  put  the  alizarin  in  the  crucible,  heat  gently  till  the 
crystals  begin  to  appear  in  the  funnel.  Then  remove  the  flame, 
or  lower  it,  and  allow  the  whole  to  stand  till  the  sublimation 
is  complete.  If  the  apparatus  shown  in  Fig.  27  is  available, 


Fig.  27. 

better  results  may  be  obtained  in  the  sublimation.  The  apparatus 
was  designed  by  Bruhl  and  consists  of  a  hollow  plate  which  can 
be  cooled  with  a  current  of  water  and  covered  above  with  a 
glass  dish  having  a  ground  edge  to  fit  the  plate  closely.  Yield 
2  to  3  grams.  By  use  of  an  autoclave  the  yield  of  crude  alizarin 
is  about  7  grams. 

Alizarin  crystallizes  in  long,  orange-red  prisms,  which  melt  at 
289° -290°.  It  boils  with  some  decomposition  at  430°,  but  may 
be  sublimed  even  at  140°.  It  is  almost  insoluble  in  cold  water, 
easily  soluble  in  alcohol,  and  ether.  It  dissolves  in  alkalies  to  a 
purple  solution.  In  dyeing  with  it,  an  aluminium  mordant  gives 
a  red,  a  ferric  salt  a  violet,  and  a  chromium  salt  a  reddish  brown. 
By  distillation  with  zinc  dust,  alizarin  is  reduced  to  anthracene, 
the  reaction  which  first  led  to  a  knowledge  of  its  composition. 
(Graebe  and  Liebermann:  Ber.,  i,  49). 


Chapter  V 

ETHERS 

Methyl  ether,  ethyl  ether  and  some  of  their  homologues  as  well 
as  some  mixed  ethers  may  be  prepared  by  distilling  a  mixture 
of  the  corresponding  alcohols  with  concentrated  sulphuric  acid. 
The  reaction  involves  two  steps  which  proceed  side  by  side. 

ROH  +  H2S04  =  RHS04  +  H2O. 
RHSO4  +  ROH  =  R— O— R  +  HaSO4. 
In  the  first  reaction  the  alcohol  reacts  as  a  base,  in  the  second 
it  reacts  as  an  acid. 

Krafft  has  shown  that  benzene  sulphonic  acid  may  be  used  to 
advantage  in  place  of  sulphuric  acid.  Ber.,  26,  2830. 

Ethers  may  also  be  prepared  by  the  action  of  alkyl  halides  or 
of  alkyl  sulphates  upon  the  sodium  derivative  of  an  alcohol. 

C2H5ONa  +  C2H5I  =-.   (C2H5)2O  +  Nal. 
C6H5ONa  +  (CH3)2S04  =  C2H5OCH3  +  NaCH3SO4. 
C6H5ONa  +  NaCH,SO4  =  C6H8OCH8  +  Na2SO4. 


29.  Preparation  of  an  Ether  by  Means  of  Concentrated  Sul- 
phuric Acid.— Ethyl  ether,  C2H5  —  O  —  C2H5. 

Literature — Theory  of  etherification,  Williamson:  Papers  on  etherifica- 
tion;  Alembic  Club  reprint;  see  also  Quart.  J.  Chem.  Soc.,  4,  229,  (1852)  ; 
Ann.,  77,  37;  8l»  73',  Nef :  Ann.,  309,  141;  318,  50;  Velocity  of  the  re- 
action, Conrad  and  Bruckner:  Z.  physik.  Chem.,  4>  631;  Use  of  sul- 
phonic acids,  Krafft:  Ber.,  26,  2829;  Combination  of  ether  and  of  ethyl 
alcohol  with  magnesium  bromide,  Menschutkin :  Z.  anorg.  Chem.,  49,  34 ; 
52,  9- 

zoo  g.  alcohol    (125  cc.). 

180  g.  concentrated  sulphuric  acid  (100  cc.). 

100  g.  alcohol. 

Put  100  grams  of  alcohol  in  a  500  cc.  flask  or  distilling  bulb, 
add  in  portions,  with  cooling,  180  grams  of  concentrated  sul- 
phuric acid.  Fit  the  mouth  of  the  flask  with  a  cork  bearing  a 


82  ORGANIC    CHEMISTRY 

thistle  tube  dipping  below  the  surface  of  the  mixture  and  carry- 
ing a  stopper  through  which  passes  a  separatory  funnel  with  a 
short  stem  as  shown  in  Fig.  20,  p.  46,  also  a  thermometer  dipping 
into  the  liquid  and  a  bent  tube  connecting  with  a  Liebig's  con- 
denser. In  all  cases  such  connections  with  the  condenser  should 
be  made  with  a  tightly  fitting  cork  stopper  and  the  stopper  in  the 
flask  is  also  best  of  cork,  as  ether  softens  india  rubber.  Heat 
the  mixture  on  a  wire  gauze  or  asbestos  plate  till  it  reaches  a 
temperature  of  140°.  Then  allow  the  alcohol  to  drop  in  slowly 
and  boil  gently,  maintaining  a  temperature  of  I4O°-I45°  by  regu- 
lating the  flow  of  alcohol  and  the  height  of  the  flame.  Allow  100 
grams  of  alcohol  to  flow  into  the  mixture. 

Transfer  the  distillate  to  a  separatory  funnel,  add  25  to  50  cc. 
of  water  and  enough  sodium  hydroxide  so  that  after  vigorous 
shaking  the  lower,  aqueous  layer  reacts  strongly  alkaline.  In 
shaking  a  mixture  of  ether  and  an  aqueous  solution  the  stopper  of 
the  separatory  funnel  should  be  held  firmly  in  place  and  after 
shaking  for  a  moment  the  stem  of  the  funnel  should  be  turned 
upward  and  the  stop-cock  opened  to  relieve  any  pressure  within. 
Allow  the  liquids  to  separate  in  two  layers,  draw  off  the  aqueous 
layer  below,  add  some  water  and  repeat  the  shaking  and  sepa- 
ration. 

Hther  is  very  volatile  and  mixtures  of  ether  vapor  and  air 
are  explosive,  hence  great  care  to  avoid  the  neighborhood  of 
flames  must  always  be  observed  .in  working  with  ether.  In  dis- 
tilling, efficient  condensers  fed  with  cold  water  should  be  used 
and  the  distillation  must  not  be  so  rapid  that  vapors  will  escape 
from  the  lower  end  of  the  condenser. 

Pour  the  washed  ether  from  the  top  of  the  separatory  funnel 
(why  not  draw  it  off  below?)  into  a  flask  containing  10  to  15 
grams  of  powdered  calcium  chloride.  After  some  hours  or  on 
the  following  day  filter  the  ether  through  a  dry  filter  into  a  dis- 
tilling bulb  and  distil  from  a  water-bath  which  is  not  heated 
above  40°. 

Ether  prepared  as  above  still  retains  small  amounts  of  alco- 
hol and  of  water.  The  alcohol  can  not  be  removed  by  washing" 


ETHERS  83 

with  water.  Metallic  sodium  in  the  form  of  wire  will  remove 
the  water  but  after  the  water  is  removed  its  action  on  the  alco- 
hol is  very  slow.  Magnesium  bromide1  will  remove  both  alco- 
hol and  water  very  perfectly  and  absolute  ether  is  best  prepared 
in  this  manner.  Allow  the  ether  to  stand  for  a  day  with  some 
of  the  powdered  magnesium  bromide  and  distil.  To  the  dis- 
tillate add  some  fresh  magnesium  bromide  and  distil  after  three 
or  four  days,  on  a  water-bath  not  heated  above  40°.  (L.  W. 
Andrews,  loc.  cit.). 

Ullmann  recommends  the  removal  of  the  alcohol  and  most  of 
the  water  by  shaking  with  1/6  of  its  volume  of  sulphuric  acid 
diluted  with  an  equal  volume  of  water.  The  ether  may  <;hen 
be  dried  with  sodium  wire. 

Pure  ether  boils  at  34.6°  and  has  a  density  at  i5°/4°  =  0.7191 
or  at  25°/4°  =  0.7079. 

Ether  free  from  alcohol  is  not  colored  by  shaking  it  with 
aniline  violet,  while  a  color  is  given  to  it,  if  alcohol  is  present. 

The  purity  of  the  ether  and  the  •  amount  of  alcohol  pres- 
ent may  also  be  determined  by  the  index  of  refraction  measured 
with  a  Pulfrich,  inversion  refractometer.  For  pure  ether  An- 
drews, gives,  subject  to  revision,  the  values: 

N/>  at  15°  =  1.35514 
N^  at  20°  -  1.35224 
N^at  25°  =  1-34933 

One  per  cent,  of  alcohol  increases  the  index  of  refraction 
at  25°  to  1.34992,  an  increase  of  0.00059. 


30.  Preparation  of  an  Ether  from  the  Sodium  Salt  of  a  Phenol 
and  Dimethyl  Sulphate. — Anisole.  Phenyl  methyl  ether,  C6H5  - 
O  —  CH3. 

Literature — Preparation  from  anisic  acid,  Cahours:  Ann.,  41,  68;  48, 
65;  52,  327;  74»  298;  From  phenol,  potassium  hydroxide  and  methyl  iodide, 
Cahours :  Ann.,  78,  227 ;  From  phenol,  sodium  hydroxide  and  dimethyl 
sulphate,  Ullmann:  Ann.,  327>  114;  Graebe:  34°»  208;  Ullmann:  Organ- 
isch-Chemisches  Pratikum,  p.  160. 

1  Prepared  by  mixing  magnesium  bromide  with  4  or  5  per  cent,  of  ammonium  brom- 
ide, drying  the  mixture  and  heating  till  the  ammonium  bromide  is  expelled.  The  state- 
ments her*-  given  are  from  a  paper  on  "The  Manufacture  of  Absolute  Hther,"  read  before 
the  Iowa  Section  of  American  Chemical  Society  at  Grinnell,  April  30,  1910. 


84  ORGANIC   CHEMISTRY 

1 8.8  grams   phenol. 

10  grrams  sodium  hydroxide. 

70  cc.  water. 

24  cc.  dimethyl  sulphate. 

9  grams  sodium  hydroxide. 

1 8.8  grams  phenol. 

Under  a  hood  with  a  good  draft1  mix  in  a  200  cc.,  not  too 
thin,  round-bottomed  flask  18.8  grams  of  phenol,  10  grams  of 
sodium  hydroxide  dissolved  in  about  70  cc.  of  water2  and  24 
cc.  of  dimethyl  sulphate.  Stopper  and  shake  vigorously,  remov- 
ing the  stopper  from  time  to  time  to  relieve  the  pressure  and 
cooling,  if  necessary,  to  keep  the  temperature  below  5o°-6o°. 
When  the  temperature  no  longer  tends  to  rise,  connect  with  an  up- 
right condenser  and  boil  for  a  few  minutes,  adding  more  sodium 
hydroxide,  if  necessary  to  maintain  an  alkaline  reaction.  Cool  and 
separate  the  solution  of  methyl  sodium  sulphate  from  the  anisole 
(about  21  grams)  by  means  of  a  separatory  funnel. 

To  the  aqueous  solution  add  9  grams  of  sodium  hydroxide 
and  1 8.8  grams  of  phenol,  connect  with  a  condenser  placed  at  an 
angle,  since  the  mixture  bumps  badly,  and  boil  for  6-7  hours. 
On  account  of  the  bumping  both  flask  and  condenser  must  be 
securely  clamped.  Add  more  sodium  hydroxide,  if  necessary, 
to  maintain  an  alkaline  reaction. 

Cool,  separate  the  anisole  as  before,  add  it  to  the  first  portion, 
dry  with  calcium  chloride,  filter  on  a  dry  filter  and  distil.  Yield 
38  grams. 

Anisole  boils  at  155°  and  has  a  specific  gravity  of  0.9878  at 

2I°/4°. 

31.  Preparation,  of  an  Ether  from  the  Sodium  Salt  of  a  Phenol 
and  an  Aryl  Halide  with  Metallic  Copper  as  a  Catalyzer.  Phenol 

/C02H 
ether  of  salicylic  acid,    C6H4^ 

\0-C6H5 

1  Dimethyl  sulphate  is  poisonous  and  breathing  of  its  vapor  must  be  carefully  avoided. 

8  II  is  very  convenient  to  have  in  the  laboratory  a  solution  of  sodium  hydroxide  of 
such  strength  that  3  cc.  =  i  gram  NaOH,  for  many  purposes  like  this.  30  cc.  of  such  a 
solution  and  40  cc.  of  water  would  be  used  here. 


ETHERS  85 

Literature. — Use  of  copper  as  a  catalyzer;  Ullmann :  Ber.,  38*  2211 ;  Ann., 
355»  312;  Preparation  of  phenol  ether  of  chlorosalicylic  acid,  Ibid,  355t 
366,  361 ;  Preparation  from  o-diazonium  benzoic  sulphate  and  phenol, 
Griess:  Ber.,  21,  982;  Preparation  of  phenylthiosalicylic  acid,  Goldberg: 
Ber.,  37,  4526;  Preparation  of  phenylanthranilic  acid,  Goldberg:  Ber., 
39>  1691;  Of  triphenylamine,  Goldberg  and  Niemerovsky:  Ber.,  40,  2448. 

1.53  gram  sodium. 
30  cc.  methyl  alcohol. 

13  grams  phenol. 

5.1  grams  o-chlorobenzoic  acid. 

o.i  gram  copper  powder. 

In  a  100  cc.  flask  dissolve  1.53  gram  of  sodium  (2/30  mol.)  in 
30  cc.  of  absolute  methyl  alcohol.  Add  13  grams  of  phenol  and 
5.1  gram  (1/30  mol.)  of  chlorobenzoic1  acid  and  expel  the  methyl 
alcohol  at  first  on  the  water-bath  and  then  by  heating  gently  on 
an  asbestos  plate.  Add  o.i  gram  of  copper  powder  and  heat  at 
180°  till  the  mass  becomes  solid.  Cool,  dissolve  the  mass  in 
water  with  the  addition  of  a  little  sodium  carbonate,  filter,  ex- 
tract the  excess  of  phenol  with  ether,  warm  the  aqueous  solution 
for  a  short  time  in  a  porcelain  dish  or  beaker  to  expel  the  ether, 
precipitate  the  phenyl  ether  of  salicylic  acid  which  has  been 
formed  with  hydrochloric  acid,  filter  it  off  and  crystallize  it 
from  dilute  alcohol. 

The  phenyl  ether  of.  salicylic  acid  crystallizes  in  leaflets  which 
melt  at  113°.  It  is  converted  quantitatively  into  xanthone, 

sco\ 

C6HX          /C6H4,  by  warming  on  the  water-bath   with  concen- 


o/ 

trated  sulphuric  acid.     (See  44,  p.  105.) 

1  This  may  be  prepared  by  Sandmeyer's  reaction  (p.  201)  from  anthranilic  acid.    The 
yield  is  70  to  80  per  cent. 


Chapter  VI 

ALDEHYDES,    KETONES  AND  THEIR  DERIVATIVES 

Aldehydes  are  prepared  by  the  oxidation  of  primary,  ketones 
by  the  oxidation  of  secondary  alcohols,  the  oxidizing  agent  be- 
ing, usually,  potassium  or  sodium  pyrochromate  and  dilute  sul- 
phuric acid,  at  moderate  temperatures.  Beckmann's  mixture 
consisting  of  60  grams  (i  molecule)  of  potassium  pyrochromate 
(or  54  grams  of  sodium  pyrochromate),  50  grams  (2.5  mole- 
cules) of  concentrated  sulphuric  acid,  and  300  cc.  of  water,  is 
most  generally  suitable.  (Ann.,  250,  325.) 

Rx  R\      /OH        Rx 

>CHOH  +  O  =      >C<          =      >C  =  O  +  H20. 
R/  R/      X)H        R/ 

Aldehydes  are  prepared  by  distilling  a  mixture  of  a  calcium 
or  barium  salt  of  an  acid,  with  calcium  or  barium  formate,  ke- 
tones by  distilling  a  calcium  salt  of  an  acid,  or  a  mixture  of  cal- 
cium or  barium  salts.  Bibasic  acids,  in  which  the  two  carboxyl 
groups  are  separated  by  four,  five  or  six  carbon  atoms,  give  cy- 
clopentanone,  hexanone,  or  heptanone,  and  their  derivatives  by 
the  same  method.  In  most  cases  it  is  not  necessary  to  prepare 
the  calcium  salt,  but  a  mixture  of  the  acid  with  a  considerable 
excess  of  quicklime  may  be  used  instead.  As  with  most  py- 
rogenic  reactions,  the  yields  are  considerably  below  the  theoreti- 
cal, and  seconda-y  reactions,  causing  the  formation  of  alcohols 
and  other  products,  take  place. 

In  the  aromatic  series,  aldehydes  may  be  prepared  by  treating 
hydrocarbons  with  chromyl  chloride,  followed  by  water.  The 
hydrocarbon  and  chromyl  chloride  are  diluted  with  carbon  bi- 
sulphide, aud  great  care  must  be  used  to  avoid  accidents.  (ICtard: 
Ann.  chim.  phys.  [5],  22,  225;  Bornemann :  Ber.,  17,  1464.) 

/O  —  CrCl2OH 
RCH3  +  2CrO,Cl2     =     R  -  CH< 

XO  -  CrCl2OH 


ALDEHYDES,    KETONES    AND    THEIR    DERIVATIVES  87 

/O  —  CrCl.OH  /OH 

R  —  CH<  -f  H20    =    RCHO  +  2CrCl/ 

X)  —  CrCl2OH  XOH 

Monochlor  derivatives  having  the  group  CH2C1  are  often  con- 
verted into  aldehydes  by  boiling  with  an  aqueous  solution  of 
some  nitrate. 

/H 

R  —  CH2C1  +  O     =      R—  C<        +  HC1. 


Ketones  are  prepared  by  the  action  of  chlorides  of  acids 
on  zinc  alkyls,  or  in  the  aromatic  series,  on  hydrocarbons  in  the 
presence  of  aluminum  chloride. 

R  ^OZnR  . 

RCOC1  -f  Zn/  "  =    R—  C—  R 

XR  \ci 

xOZuR 
R  -  C—  R          +  RCOC1  2R—  CO-R  +  ZnCl,. 

NCI 

or 

/0ZnR 
R  —  C—  R          +  H,0  =  R  —  CO  -  R  +  Zn<  +  RH. 

\ci  Xci 

RH  +  RCOC1  +  A1C1,     =     R—  CO—  R  +  HC1  +  A1C1,. 

Practically,  the  use  of  zinc  alkyl  compounds  has  been  displaced 
by  the  organomagnesium  compounds  as  used  in  the  Barbier- 
Grignard  reaction  (p.  67). 

Ketones  are  prepared  from  acetoacetic  ester  and  similar  com- 
pounds by  the  "ketonic  decomposition."  (See  p.  -112.) 

Aldehydes  and  ketones  may  be  prepared  by  warming  an  a- 
hydroxy  acid  with  lead  peroxide  and  sulphuric  acid.  (Baeyer: 
Ber.,  30,  1962;  Noyes  and  Shepherd:  Am.  Chem.  J.,  22,  264.) 

R—CHOHCCXH  +  PbO2  +  H,SO4    =     R—  CHO  +  PbSO4 
+   C02   +   2H20. 


88  ORGANIC   CHEMISTRY 

* 

R\ 

>COH.C02H  +  Pb02  +  H2SO4  = 
R' 

R 


R 


\ 
> 

/ 


CO  +  PbSO4  -}-  CO2  +  2H2O. 


The  sodium  salts  of  aliphatic  nitro  compounds  are  decomposed 
by  acids  with  the  formation  of  aldehydes  or  ketones.  (Nef: 
Ann.,  280,  267.) 

2R—  CH=NO—  ONa  +  2HC1     =  2R—  CHO  +  2NaCl 
+  N20  +  H20. 

Many  glyoxylic  acids  are  decomposed  by  heat  with  the  for- 
mation of  aldehydes.  (Bouveault:  Bull.  soc.  chim.  [3],  17, 
363.)  Glyoxylic  acids  may  be  prepared  by  the  method  of  Ver- 
ley,  p.  107. 

RCOCO2H     =     R—  CHO  +  CO2. 

In  the  aromatic  series,  aldehydes  may  be  prepared  by  the 
careful  oxidation  of  cinnamic  acid  and  its  derivatives,  in  alka- 
line solution,  by  means  of  potassium  permanganate.  This  is  in 
some  sense  the  reverse  of  the  preparation  of  cinnamic  acid  from 
benzaldehyde. 

R—  CH=CH—  CO2H  +  40     =     R—  CHO  +  2CO2  +  H2O. 
(Einhorn:  Ber.,   17,   121.) 

Quinones  are  usually  prepared  by  the  oxidation  of  aniline  and 
its  homologues,  having  a  hydrogen  atom,  or  a  hydroxy  or 
amino  group  in  the  para  position  to  the  amino  group.  Po- 
tassium or  sodium  pyrochromate  and  sulphuric  acid  are  usually 
employed.  In  some  cases,  (e.  g.,  anthracene),  a  hydrocarbon  can 
be  oxidized  directly  to  a  quinone.  The  reaction  in  the  case  of 
compounds  containing  the  amino  group  is  complicated,  and  can- 
not be  expressed  by  a  simple  reaction  (see  27,  p.  76). 

Aldehydes  and  ketones  are  very  reactive  bodies,  passing  readi- 
ly into  alcohols  and  acids  by  reduction,  or  oxidation,  and  con- 
densing very  easily  with  a  great  variety  of  other  substances, 
which  makes  them  especially  valuable  for  synthetical  purposes. 
The  most  characteristic  condensation  products,  and  those  most 


ALDEHYDES,    KETONES    AND    THEIR    DERIVATIVES  89 

often  used  for  purposes  of  identification  and  purification,  be- 
cause of  their  crystalline  character,  are  the  double  compounds 
with  acid  sulphites  of  the  alkali  metals;  the  phenylhydrazones, 
(E.  Fisher:  Ber.,  17,  572;  21,  984;  22,  90)  ;  Oximes,  (V.  Meyer 
and  Janny:  Ber.,  15,  1324,  1525);  And  the  semicarbazones, 
(Baeyer:  Ber.,  27,  1918;  Thiele  and  Stange:  Ann.,  283,  i ;  Thiele 
and  Heuser;  Ibid,  288,  311). 

OH 
R  R        / 

NcO  -f  NaHSO3  =     Nc— SO3Na. 
R/  R/ 

Double  compound  with 
hydrogen  sodium  sulphite. 


:> 


:0  -f  C6H5NHNH2     =        >C=N  —  NHC6H5  -f  H2O. 

R/ 

Phenyl  hydrazone 

Rx  R\ 

>CO  -f  NH2OH     =        >C=NOH  +  H3O. 
R/  R/ 

Oxime. 

CO  -f  NH2— NH— CO— NH2  = 

R\ 

>C  =  N  —  NH  —  CONH2  +  H2O. 

R/ 

Semicarbazone. 


32.  Preparation  of  an  Aldehyde  by  Oxidation  of  a  Primary 

/H 
Alcohol.—  Acetaldehyde,    CH3C<  (Ethanal). 


Literature  —  Liebig:  Ann.,  14,  133;  Ritter:  Ibid,  97,  369;  Stadeler: 
Jahresb.,  1859,  329;  J.  prakt.  Chem.,  76,  54,  (1859);  Bourcart  ;  Z.  anal. 
Chem.,  29,  609;  Rogers:  J.  prakt.  Chem.,  4°,  240,  (1847);  Weidenbusch: 
Ann.,  66,  152;  Limpricht:  Ibid,  97,  369;  Tollens:  Ber.,  14,  1950;  Orndorff 
and  White  :  Am.  Chem.  J.,  16,  43. 

150  grams  (81  cc.)  concentrated  sulphuric  acid. 

300  cc.  water. 


90  ORGANIC   CHEMISTRY 

100  grams  sodium  pyrochromate. 

150  cc.   water. 

75  grams  (95  cc.)  alcohol. 

Put  in  a  one  liter  distilling  bulb  300  cc.  water,  and  150  grams 
(81  cc.)  of  concentrated  sulphuric  acid.  Dissolve  100  grams 
of  sodium  pyrochromate  in  150  cc.  of  water,  and  add  75  cc.  of 
alcohol.  Put  a  stopper  bearing  a  separatory  funnel  in  the  mouth 
of  the  distilling  bulb,  and  connect  a  second  250  cc.  distilling 
bulb  to  its  side  tube  with  a  rubber  stopper.  Connect  the  side 
tube  of  the  second  bulb  to  a  condenser  which  is  directed  upward, 
by  running  the  side  tube  into  a  piece  of  rubber  tubing  drawn  over 
the  lower  end  of  the  condenser.  Connect  the  upper  end  of  the 
condenser  with  two  wash-bottles  fitted  with  cork  stoppers,  or 
with  two  Dreschel  wash-bottles  each  containing  about  25  cc.  of 


Fig.  28. 


dry  ether.  Surround  the  latter  with  a  freezing  mixture.  Put  the 
small  distilling  bulb  into  a  dish  containing  water  at  45°-5O°,  and 
feed  the  condenser  with  water  at  30°.  Heat  the  dilute  sulphuric 
acid*  nearly  to  boiling,  remove  the  flame,  and  drop  in  the  pyro- 
chromate mixture  slowly.  The  reaction  may  proceed  as  rapidly 
as  is  possible  without  escape  of  aldehyde  through  the  ether. 
Outside  heating  is  not  usually  necessary  after  the  reaction  has 
commenced. 


ALDEHYDES,  KETONES  AND  THEIR  DERIVATIVES  91 

When  all  the  mixture  has  been  added  and  the  aldehyde  driven 
over,  by  heating  for  a  short  time,  disconnect  the  wash-bottle, 
transfer  the  ethereal  solution  to  a  flask,  set  the  latter  in  a  freez- 
ing mixture,  and  pass  in  ammonia  gas,  generated  by  boiling 
strong  aqua  ammonia  (0.90  sp.  gr.),  and  dried  by  passing  it  over 
quicklime,  or  soda-lime  in  a  drying  cylinder.  Use  a  wide  de- 
livery tube  for  the  gas  to  prevent  its  being  stopped  by  the  alde- 


hyde  ammonia,  CH3CH  ,  which  is  formed.       Pass  the  gas 

\NH2 

till  the  solution  smells  strongly  of  ammonia,  and  allow  the  whole 
to  stand  for  an  hour.  Filter  off  the  crystals,  and  allow  them  to 
stand  on  filter  paper  for  a  short  time.  They  can  be  kept  for 
some  time  in  tightly  stoppered  tubes  or  bottles,  containing  am- 
monia gas.  Yield  about  15  grams. 

Aldehyde  may  be  prepared  from  the  crystals  by  dissolving 
them  in  their  own  weight  of  water,  and  dropping  the  solution  into 
4  parts  of  50  per  cent,  sulphuric  acid,  condensing  the  aldehyde 
which  is  generated,  with  a  condenser  containing  ice-water,  and 
collecting  in  a  flask  surrounded  with  a  freezing  mixture. 

Aldehyde  boils  at  21°,  and  has  a  specific  gravity  of  0.7951 
at  10°.  When  warmed  with  caustic  potash  it  is  converted  into 
a  resin.  It  reduces  a  cold  ammoniacal  solution  of  silver  nitrate 
(3  grams  AgNO3,  33  cc.  NH4OH,  sp.  gr.  0.90,  30  cc.  10  per  cent. 
sodium  hydroxide),  a  general  reaction  for  aldehydes.  It  restores 
the  color  of  a  fuchsine  solution  which  has  been  decolorized  by 
sulphur  dioxide.  A  drop  of  concentrated  sulphuric  acid  con- 
verts it  into  paraldehyde,  C6H12O3,  which  melts  at  10.5°,  and 
boils  at  124°.  Hydrochloric  acid  gas  converts  it  into  a  mixture 
of  metaldehyde,  C6H12O3,  and  paraldehyde.  Metaldehyde  decom- 
poses on  standing,  being  converted  partly  into  paraldehyde  and 
partly  into  tetraldehyde,  C8H16O4.  Paraldehyde  and  metaldehyde 
are  probably  stereomeric  compounds.  Orndorft  and  White,  loc. 
cit.,  Hantsch,  however,  Ber.,  40,  4341,  considers  metaldehyde  as 
tetramolecular,  (C2H4O)4,  or  hexamolecular,  (C2H4O)6.) 


92  ORGANIC   CHEMISTRY 

33.  Preparation  of  a  Ketone  by  the  Distillation  of  a  Calcium 
Salt.— Acetone,  (Propanone),  CH3COCH3. 

Literature. — Preparation  from  acetates,  Liebig:  Ann.,  i,  225;  Dumas. 
Ann.  chim.  phys.  (2),  49»  208;  By  the  dry  distillation  of  wood,  Volckel: 
Ann.,  80,  310;  By  the  oxidation  of  citric  acid,  Pean:  Jahresb.,  1858, 
585;  From  acetyl  chloride  and  zinc  methyl,  Freund:  Ann.,  118,  u. 

20  grams  glacial  acetic  acid. 

40  cc.  water. 

35  grams  barium  carbonate. 

Mix  20  grams  of  glacial  acetic  acid  with  40  cc.  of  water  in  a 
not  too  small  porcelain  dish,  add  in  portions  35  grams  of  baiium 
carbonate  and  evaporate  the  mixture  rapidly  to  dryness  on  an 
asbestos  plate,  avoiding  over  heating  after  the  water  has  been  ex- 
pelled. Put  the  dry  residue  in  a  hard  glass  tube  20  cm.  long  and 
25-30  mm.  in  diameter.  Connect  with  a  condenser  by  means 
of  cork  stoppers  and  a  bent  glass  tube  and  distil  with  a  free  flame, 
holding  the  burner  in  the  hand  to  secure  uniform  heating  of  the 
whole  mass.1  Shake  the  distillate  twice  with  2-3  cc.  of  a  concen- 
trated solution  of  potassium  carbonate  to  remove  acids,  dry  with 
calcium  chloride  and  distil  from  a  small  distilling  bulb,  using  a 
water-cooled  condenser  and  collecting  the  portion  boiling  at  54°- 
60°,  in  a  dry  weighed  flask.  Weigh  the  distillate  and  add  to  it 
2.^/2  times  its  weight  of  acid  sodium  sulphite  dissolved  in  its  own 
weight  of  warm  water.  When  the  double  compound  has  com- 
pletely separated,  filter  it  off  on  a  plate  or  a  Hirsch  funnel  (p.- 
120)  suck  it  as  dry  as  possible,  stop  the  pump  moisten  with  a 
few  drops  of  water,  suck  this  off  after  a  few  minutes  and  repeat 
a  second  time.  Dry  the  compound  on  a  filter-paper. 

Decompose  one  gram  of  the  compound  by  mixing  it  with  one 
gram  of  dry  sodium  carbonate  and  10  cc.  of  water  and  distilling. 
Test  the  distillate  with  the  iodoform  reaction  (p.  207). 

Acetone  boils  at  56.5°  and  has  a  specific  gravity  of  0.7920  at 
19.8°.  It  reacts  readily  with  hypochlorites  giving  chloroform, 
or  with  hypobromites  or  hypoiodites  giving  bromoform  or  iodo- 
form. 

1  Distillation  from  a  small  distilling  bulb  immersed  in  a  bath  of  Wood's  metal  will 
tive  better  yields. 


AI45EHYDES,    KETONES    AND    THEIR    DERIVATIVES  93 


3V 

34.    Preparation  of  an  Oxime.—  Acetoxime,  ^>C=NOH 

CH/ 

(Isonitroso  acetone  or  propanone  oxime). 

Literature—  V.  Meyer  and  Janny:  Ber.,  i5i  1324,  1529;  Janny:  Ibid, 
16,  170;  V.  Meyer  and  Wege  :  Ann.,  264,  121;  Dodge:  Ibid,  264,  185; 
Beckmann:  Ber.,  21,  767;  Auwers  :  Ibid,  22,  604. 

15  grams  hydroxylamine  hydrochloride. 
14  grams   (17  cc.)   acetone. 
8  grams  sodium  hydroxide. 

50  cc.  water. 

* 

Put  in  a  100  cc.  glass  stoppered  bottle,  15  grams  of  hydroxyl- 
amine hydrochloride,  and  17  cc.  of  acetone,  and  add  a  solution 
of  8  grams  of  sodium  hydroxide  in  50  cc.  of  water.  Shake  and 
cool  somewhat,  stopper  tightly,  and  allow  to  stand  for  twenty- 
four  hours.  Extract  the  solution  three  times  with  about  20  cc. 
of  ether,  the  ether  being  distilled  off  and  used  again  each  time, 
because  of  the  volatility  of  the  acetoxime.  The  last  time  distil 
only  about  one-half  of  the  ether,  transfer  the  remainder  of  the 
ethereal  solution  to  a  crystallizing  dish,  and  allow  the  ether  to 
evaporate  spontaneously,  or  better  in  vacua  over  sulphuric  acid. 
As  soon  as  the  crystals  are  dry,  transfer  to  a  well  stoppered 
bottle,  as  the  substance  is  quite  volatile.  Yield  14  to  15  grams. 

In  the  preparation  of  acetoxime,  it  is  necessary  to  use  the  so- 
dium hydroxide  and  hydroxylamine  in  equivalent  amounts,  as  the 
acetoxime  cannot  be  extracted  from  an  acid  or  an  alkaline  solu- 
tion. Auwers  has  shown,  however,  that  in  some  cases  the  for- 
mation of  an  oxime  is  facilitated  by  using  about  three  times  the 
theoretical  amount  of  sodium  hydroxide. 

Acetoxime  crystallizes  in  prisms,  which  melt  at  59°-6o°.  It 
boils  at  134.8°  under  728  mm.  pressure.  It  is  very  easily  soluble 
in  water,  alcohol,  ether,  and  ligrom.  It  can  be  extracted  with 
ether  only  from  neutral,  not  from  acid,  or  alkaline  solutions.  It 
is  decomposed  by  boiling  with  hydrochloric  acid  into  acetone  and 
hydroxylamine  hydrochloride. 


94  ORGANIC   CHEMISTRY 

35.  Preparation   of   a   Semicarbazone    Compound.  —  Semicarba- 


zone  of  acetone,  >C^N—  NH—  CONH2. 

CH/ 

Literature  —  Thiele  and  Stange:  Ann.,  283,  19;  Thiele,  Lachman  and 
Heuser:  Ibid,  288,  311;  Baeyer  :  Ber.,  27,  1918. 

70  cc.  concentrated  sulphuric  acid. 

20  grams  nitrate  of  urea. 

Ice. 

20  grams  nitrourea. 
150  cc.  concentrated  hydrochloric  acid. 
'  70  grams  zinc  dust. 
Ice. 

Salt. 

20  grams  sodium  acetate. 

12  grams  acetone. 

Put  70  cc.  of  concentrated  sulphuric  acid  in  a  beaker  and  cool 
it  below  o°  with  a  freezing  mixture.  Add  20  grams  of  dry  urea 
nitrate,1  in  small  portions,  stirring,  and  taking  care  that  the 
mixture  does  not  rise  above  2°-3°.  Allow  to  stand  for  half  an 
hour,  but  not  after  there  is  much  evolution  of  gas.  Pour  on 
such  a  quantity  of  ice  that  the  temperature  of  the  mixture  is 
about  30°.  Cool,  filter,  wash  slightly,  and  suck  as  dry  as  possible. 
Stir  in  with  150  cc.  of  concentrated  hydrochloric  acid,  previously 
cooled  to  o°,  and  containing  some  pieces  of  ice.  Pour  in  small 
portions,  into  a  mixture  of  70  grams  of  zinc  dust,  with  powdered 
ice,  keeping  the  whole  in  a  beaker,  or,  especially  In  working  with 
larger  quantities  in  a  granite  iron  dish,  placed  in  a  freezing 
mixture.  The  temperature  should  be  kept  at  about  o°,  but  the 
use  of  much  ice  in  the  solution  should  be  avoided,  because  of  the 
resulting  dilution.  After  all  has  been  added,  allow  to  stand  for 
a  short  time,  filter,  add  salt  to  saturation,  and  20  grams  of  so- 
dium acetate,  and  filter  again,  if  necessary.  These  operations 

i  This  may  be  prepared  as  follows:  Dissolve  12  grams  of  urea  in  12  cc.  of  water,  and 
pour  the  solution  into  20  cc.  of  concentrated  nitric  acid,  diluted  with  20  cc.  of  water.  Cool 
thoroughly,  filter  on  a  plate,  and  dry  on  filter  paper,  or  porcelain.  20  to  22  grams  should 
be  obtained. 


ALDEHYDES,   KETONES  AND  THEIR  DERIVATIVES  95 

should  be  carried  through  rapidly,  and  the  solution  not  allowed 
to  become  warm.  Add  12  grams  (15  cc.)  of  acetone,  stir  thor- 
oughly, and  allow  to  stand  for  some  hours,  if  necessary  over 
night,  in  a  freezing  mixture,  or  til"?  the  double  compound  of  zinc 
with  the  acetone  semicarbazone, 


r 

>C=N  —  NH—  CO—  NHS  |    ZnCl2, 
ICH/  J, 

has  separated  as  completely  as  possible.  Filter  off,  wash  with 
a  little  salt  solution,  and  a  little  ice-water.  16  to  18  grams  of  the 
compound  should  be  obtained. 

By  adding  some  benzaldehyde  to  the  filtrate,  stirring  thor- 
oughly, and  allowing  to  stand,  a  small  quantity  of  the  semicar- 
bazone of  benzaldehyde  can  be  obtained. 

To  obtain  the  acetone  semicarbazone,  digest  15  grams  of  the 
salt  with  30  cc.  of  concentrated  ammonia  for  some  time,  and  fil- 
ter. 

To  'prepare  the  hydrochloride  of  semicarbazine,  add  to  the  ace- 
tone compound  twice  its  weight  of  concentrated  hydrochloric 
acid,  and  filter  through  a  funnel  loosely  plugged  with  asbestos. 
Allow  the  solution  to  stand  in  a  vacuum  desiccator  containing 
soda-lime  and  concentrated  sulphuric  acid,  till  it  evaporates  nearly 
to  dryness.  Dry  the  crystals  of  the  chloride  on  porous  porcelain. 

Acetone  semicarbazone  crystallizes  in  needles,  which  melt  with 
decomposition  at  187°.  It  is  moderately  soluble  in  cold  water, 
less  soluble  in  alcohol,  insoluble  in  ether.  It  reduces  an  ammo- 
niacal  silver  solution  immediately.  It  is  easily  decomposed  by 
mineral  acids,  even  in  the  cold. 

The  hydrochloride  of  semicarbazine,  NHaCO—  NH—  NH2— 
HC1,  crystallizes  in  prisms,  which  melt  at  173°  with  decomposi- 
tion. It  dissolves  very  easily  in  water,  less  easily  in  hydrochloric 
acid,  and  is  almost  insoluble  in  alcohol,  and  ether.  It  is  decom- 
posed by  heating  with  acids  and  alkalies.  It  condenses  readily 
with  most  ketones  and  aldehydes,  forming,  usually,  well  crystal- 
lized compounds. 

For  the  preparation  of  semicarbazones,  Baeyer  and  Thiele  re- 


96  ORGANIC   CHEMISTRY 

commend  to  dissolve  the  hydrochloride  of  semicarbazine  in  a  little 
water,  add  the  calculated  amount  of  an  alcoholic  solution  of  po- 
tassium acetate  and  the  ketone,  and  then  alcohol  and  water  to 
complete  solution.  The  reaction  is  complete  in  a  few  minutes 
in  some  cases,  in  others  it  requires  4  to  5  days.  When  complete, 
the  addition  of  water  will  usually  cause  the  separation  of  a  sub- 
stance which  is  entirely  crystalline. 

36.  Preparation  of  an  Aldehyde  by  Treatment  of  a  Monochlor 
Derivative  of  an  Aromatic  Hydrocarbon  with  a  Nitrate.  —  Benzal- 

/H 
dehyde,    CgH^^       .     (Oil  of  bitter  almonds.) 


Literature  —  Liebig,  Wohler:  Ann.,  22,  i;  C'annizzaro:  Ibid,  88,  129; 
Dumas,  Peligot:  Ibid,  14,  50;  Guckelberger  :  Ibid,  64,  60;  72,  86;  Lauth, 
Grimaux:  Bull.  soc.  chim.,  7»  106;  Piria:  Ann.,  100,  105;  Limpricht: 
Ibid,  139,  319;  Anschiitz:  Ibid,  226,  18. 

40  grams  benzyl  chloride. 

40  grams  barium  nitrate. 

300  cc.  water. 

Put  in  a  500  cc.  round-bottomed  flask  40  grams  of  benzyl 
chloride,  40  grams  of  barium  nitrate  (or  30  grams  of  calcium  ni- 
trate, prepared  by  treating  an  excess  of  calcium  carbonate  with 
the  theoretical  amount  of  nitric  acid,  and  filtering),  and  300  cc. 
of  water.  Connect  with  an  upright  condenser,  best  with  a  rubber 
tube  slipped  over  the  neck  of  the  flask,  the  condenser  reaching 
well  down  into  the  neck  of  the  latter,  so  that  the  nitrous  fumes 
evolved  will  come  but  little  in  contact  with  the  rubber.  The 
connection  must  be  tight.  Put  in  the  top  of  the  condenser  a 
rubber  stopper  bearing  a  tube,  which  reaches  down  into  the 
liquid,  and  also  a  tube  which  will  convey  the  gases  coming  from 
the  condenser  to  the  bottom  of  a  150  cc.  bottle,  or,  better,  of  a 
large  tube,  closed  below.  Pass  through  the  first  tube  a  slow 
current  of  carbon  dioxide,  and  boil  the  contents  of  the  flask  gent- 
ly, on  a  wire  gauze,  for  six  or  eight  hours,  or  till  the  odor  of  the 
benzyl  chloride  nearly,  or  quite  disappears.  Some  such  means  as 
that  described  for  the  exclusion  of  the  air  is  essential  to  prevent 
the  oxidation  of  the  aldehyde  to  benzoic  acid. 


ALDEHYDES,   KETONES  AND  THEIR  DERIVATIVES  97 

Extract  the  benzaldehyde  with  ether,  distil  off  the  latter,  and 
shake  the  residue  with  three  or  four  times  its  volume  of  a  strong 
solution  of  acid  sodium  sulphite,1  in  a  stoppered  bottle.  After 
some  time,  filter  off  the  bisulphite  compound  and  wash  succes- 
sively with  a  very  little  water,  alcohol,  and  ether.  Put  the  com- 
pound in  a  distilling  bulb  with  an  excess  of  a'  strong  solution  of 
sodium  carbonate,  and  distil  with  steam.  Extract  the  benzalde- 
hyde from  the  distillate  with  ether,  dry  with  calcium  chloride, 
and  distil.  Yield  10  to  15  grams. 

Benzaldehyde  melts  at — 13°. fc  and  boils  at  179°.  It  has  a 
specific  gravity  of  1.0504  at  15°.  It  oxidizes  slowly  on  standing 
.in  the  air,  when  pure.  It  is  more  stable  when  it  contains  hydro- 
cyanic acid,  which  is  usually  added  to  the  commercial  article 
for  this  reason.  It  dissolves  in  300  parts  of  water,  but  is  easily 
soluble  in  alcohol,  and  ether. 

37.  Condensation  of  an  Aldehyde  with  Itself  by  Means  of  Po- 
tassium Cyanide.— Benzoin,  C6H5CHOHCOC6H5. 

Literature — Liebig  and  Wohler:  Ann.,  3,  276;  Brewer,  Zincke :  Ibid, 
198,  151;  Papcke:  Ber.,  21,  1335;  A.  Smith  and  Ransom:  Am.  Chem. 
J.,  16,  108. 

20  grams  benzaldehyde. 

2  grams  potassium  cyanide. 

50  cc.  alcohol. 

40  cc.   water. 

Boil  the  mixture  given  above  with  an  upright  condenser  for 
half  an  hour.  Cool,  filter,  wash  with  dilute  alcohol,  and  crystal- 
lize from  a  little  hot  alcohol.  A  little  more  benzoin  may  be  ob- 
tained by  adding  a  little  more  potassium  cyanide  to  the  filtrate, 
and  boiling  again  for  a  quarter  of  an  hour.  Yield  15  to  18 
grams. 

Benzoin  melts  at  134°,  and  boils  with  some  decomposition  at 
320°.  By  warming  on  the  water-bath  for  two  hours  with  two 
and  one-half  times  its  weight  of  nitric  acid  (sp.  gr.  1.33),  with 
frequent  shaking,  it  is  oxidized  to  benzil,  C6H5COCOC6H5. 

1  This  must  be  freshly  prepared  by  passing  sulphur  dioxide  into  a  mixture  of  acid 
sodium  carbonate  with  three  parts  of  water,  till  the  solution  smells  strongly  of  the  gas 
For  sulphur  dioxide,  see  p.  78. 

7 


98  ORGANIC    CHEMISTRY 

By  means  of  fuming  hydriodic  acid  benzoin  may  be  reduced 
to  dibenzyl,  C6H5CH2CH2C6H5. 

38.  Oxidation  of  a  Secondary  Alcohol  to  a  Ketone.  —  Benzil, 
C6H5—  COCO-C6H5. 

Literature  —  Preparation  from  benzoin,  Zinin  :  Ann.,  34,  188;  Prepara- 
tion from  i.2-diphenyltetrachlorethane,  (tolantetrachloride)  and  color 
reactions  with  alcoholic  potash  :  Liebermann  and  Homeyer  :  Ber.,  12, 
1975;  Rearrangement  to  diphenyl  glycolic  acid  (benzilic  acid),  Liebig: 
Ann.,  25,  27;  Zinin:  Ann.,  31,  329;  Staudinger:  Ann.,  356,  71;  Con- 
densation with  orthodiamines  to  a  quinoxaline,  Hinsberg:  Ann.,  237, 
327;  Hinsberg  and  Konig:  Ber.,  27,  2181;  Condensation  with  ammonia 
and  aldehydes  to  glyoxalines,  Radziszewski  :  Ber.,  i5>  1494,  2706;  Pre- 
paration, Henle,  Anleitung  fur  das  organisch  preparative  Praktikum,  p. 
143- 

10  grams  benzoin. 

25  cc.  nitric  acid  (142). 

Put  in  a  small  flask  10  grams  of  benzoin  and  25  cc.  of  concen- 
trated nitric  acid,  (sp.  gr.  1.42).  Heat  on  the  water-bath  with 
frequent  shaking  till  oxides  of  nitrogen  are  no  longer  evolved 
and  a  few  drops  of  the  solution  give,  on  dilution,  a  precipitate 
which  after  washing  and  dissolving  in  alcohol  does  not  reduce 
Fehling's  solution.  Precipitate  with  water,  filter  on  a  plate,  wash 
and  recrystallize  from  alcohol.  Yield  9  grams. 

Benzil  crystallizes  from  ether  in  prisms  which  melt  at  95°. 
It  boils  at  346°-348°,  with  some  decomposition,  under  atmos- 
pheric pressure  or  at  188°  under  a  pressure  of  12  mm.  or  at  104°- 
105°  under  a  high  vacuum. 

When  fused  with  caustic  potash  and  a  little  water  benzil  rear- 


ranges  to  diphenylglycolic  acid  (benzilic  acid)  (C6H5)2-C 

XC02H 

Benzil  has  been  of  unusual  interest,  because  of  the  part  which 
its  compounds  have  played  in  the  development  of  the  theories  of 
stereo-chemistry.  It  forms  two  monoximes  and  three  dioximes, 
to  which  the  following  stereomeric  formulas  have  been  given  : 

C6H6  -  C  -  CO  -  C6H5,  C6H5  -  C  -  CO  -  CBH5, 

II  II 

HO  —  N  N  —  OH 


ALDEHYDES,  KETONES  AND  THEIR  DERIVATIVES  99 

C6H5  -  C  -  C  -  C6H5,         C.H6  -  C C  -  C6H5, 

I!      ii  ii  II 

HO  —  N       N—  OH  N  — OH    HO  — N 

C6H5  -  C C  -  C6H, 

II  II 

HO  —  N     HO  —  N 

Some  have  supposed  that  the  differences  are  due  to  structural 
isomerism  and  not  to  stereoisomerism.  See  Wittenberg  and  V. 
Meyer:  Ber.,  16,  503;  Auwers  and  V.  Meyer:  Ibid,  21,  784, 
3510;  22,  537,  564,  1985,  1996;  Hantsch  and  Werner:  Ibid,  23,  n, 
1243- 

39.  Condensation  of  an  Aldehyde  with  a  Ketone  and  Oxidation 
of  the  Acetyl  Group  with  Sodium  Hypochlorite. — Cinnamic  acid, 
C6H5CH  =  CHCCXH. 

Literature — See  preparation  of  cinnamic  acid  p.  133,  also  Engler,  Leist: 
Ber.,  6,  254,  257 ;  Claisen,  Claparede :  Ibid,  i4i  2461 ;  Claisen,  Ponder : 
Ann.,  223,  139;  J.  G.  Schmidt:  Ber.,  14,  1460;  Meister,  Lucius  and  Briin- 
ing,  D.  R.  P.,  21162,  Ibid,  16,  449;  Vorlander:  Ber.,  30,  2261,  Ann., 
294,  275:  Straus,  Caspari :  Ber.,  40,  2698.  Foot  note  4. 

10  grams  benzaldehyde. 

25  cc.  acetone. 

10  cc.  caustic  soda  (10  per  cent.). 

900  cc.  water. 

In  a  one  liter  flask  place  900  cc.  of  water,  10  grams  of  benzal- 
dehyde, 25  cc.  acetone  and  10  cc.  of  caustic  soda,  free  from  car- 
bonate. Mix 'thoroughly  by  shaking  and  allow  to  stand  for  lour 
days,  shaking  occasionally.  The  aldehyde  and  acetone  condense 
with  the  formation  of  benzalacetone,  C6H5— CH=CHCOCH3, 
and  dibenzalacetone,  C6H5— CH— CH— CO— CH=CH— C6H5. 
Add  200  grams  of  salt  (see  74,  p.  167)  and  filter  off  and  wash 
the  dibenzalacetone  if  it  is  solid,  or  extract  twice  with  a 
small  amount  of  ether,  if  it  is  liquid.  Distil  off  the  ether  ?..nd 
fractionate  the  benzalacetone  from  a  small  distilling  bulb  (see 
Fig.  34,  P-  171),  under  diminished  pressure.  The  benzalacetone 
distils  at  I5i°-i53°  under  25  mm.  pressure,  at  26o°-262°  under 
760  mm.,  and  melts  at  42°. 


IOO  ORGANIC   CHEMISTRY 

2.5  grams  benzalacetone. 
12  grams  chloride  of  lime. 
15  grams  sodium  carbonate. 
125  cc.  water. 

To  12  grams  of  chloride  of  lime  (containing  31  per  cent,  of 
available  chlorine)  add  50  cc.  of  water  and  75  cc.  of  a  solution 
of  sodium  carbonate  (5  cc.  =  i  gram  Na2CO3).  Filter  with  the 
pump  and  wash  once.  To  the  filtrate  add  2.5  grams  of  benzal- 
acetone, warm  to  80°  -90°  and  shake  vigorously.  Continue  to 
warm  and  shake  till  the  odor  of  chloroform  is  no  longer  apparent. 
The  benzalacetone  should  now  have  passed  into  solution. 

Cool,  filter,  precipitate  the  cinnamic  acid  with  sulphuric  acid 
and  recrystallize  from  hot  water.  The  oxidation  is  exactly 
analogous  to  that  by  which  chloroform  is  prepared  commercially 
from  acetone.  For  the  properties  of  cinnamic  acid  see  p.  .134. 

The  condensation  of  benzaldehyde  with  a  methyl  or  methylene 
group  adjacent  to  carboxyl  is  a  quite  general  reaction  and  may 
sometimes  furnish  a  basis  for  the  determination  of  the  structure 
of  compounds.  See  Noyes  and  Shepherd:  Am.  Chem.  J.,  22, 

265. 

40.  Preparation    of   a   Phenylhydrazone.  —  Phenylhydrazone  of 


acetophenone,  >C—  N—  NHC.H.. 


Literature  —  E.  Fischer:  Ber.,  17,  5/3;  22,  9O;  16,  2241;  Overton  :  Ibid, 
•  26,  R   18,  Reisenegger.  Ibid,  16,  661. 

5  cc.  acetic  acid   (30  per  cent.). 

1.5  cc.  phenyl  hydrazine. 

i  cc.  acetophenone. 

Dissolve  1.5  cc.  of  phenyl  hydrazine  in  5  cc.  of  acetic  acid 
(30  per  cent.)  in  a  test-tube,  add  i  cc.  of  acetophenone,  and  shake 
vigorously  till  the  hydrazone  separates  in  crystalline  form.  Fil- 
ter, wash  with  water,  dissolve  in  a  very  small  beaker,  in  a  little 
hot  alcohol,  add  water  till  the  hot  solution  begins  to  grow  turbid, 
and  allow  to  crystallize. 

The  hydrazone  of  acetophenone   is  very  easily  obtained   and 


ALDEHYDES,     KETONES    AND    THEIR    DERIVATIVES  IOI 

purified.  In  some  cases,  where  there  is  difficulty  in  obtaining 
a  crystalline  product,  Overton  (loc.  cil.)  recommends  to  dissolve 
the  ketone  in  a  little  glacial  acetic  acid,  add  a  slight  excess  of 
phenyl  hydrazine,  and  allow  the  mixture  to  stand  in  the  cold  till 
the  hydrazone  separates. 

Acetophenone  phenylhydrazone  crystallizes  from  dilute  alcohol 
in  leaflets,  which  melt  at  105°.  It  is  decomposed  by  concen- 
trated hydrochloric  acid  into  phenyl  hydrazine  hydrochloritie,  and 
acetophenone.  By  sodium  amalgam,  in  alcoholic  solution,  it  is 
reduced  to  a  mixture  of  aniline  and  phenyl  methyl  carbinamine, 
C6H5CHNH2CH.,  (V-aminoethylphen). 

41.  Preparation  of  a  Ketone  by  Condensation  of  an  Acid  Chlo- 
ride with  Benzene  by  Means  of  Aluminium  Chloride. — Benzo- 
phenone,  CgH-jCOCgH-.  (Diphenylmethanone.) 

Literature — Peligot :  Ann.?i2,  41;  Chancel:  Ibid,  7*,  279;  Otto:  Ber., 
3»  197;  Friedel,  Crafts:  Ann.  chim.  phys.,  [6],  i,  510,  518;  Zincke :  Ann., 
i59,  377;  Friedel,  Crafts,  Ador :  Ber.,  10,  1854;  Stockhansen  and  Gatter- 
mann  :  Ber.,  25,  3521;  Radziewanowski :  Ibid,  27,  3235;  28,  1135;  Crafts: 
Am.  Chem.  ].,  5,  324 ;  Preparation  by  use  of  ferric  chloride,  Nencke  and 
Stoeber:  Ber.,  30,  1768. 

20  grams  benzene. 
20  grams  benzoylchloride. 
100  grams  carbon  disulphide. 
20  grams  aluminium  chloride. 

Put  in  a  flask  20  grams  of  benzene,  20  grams  of  benzoyl  chlo- 
ride, and  100  grams  of  carbon  disulphide.  Add  in  small  por- 
tions, during  about  ten  minutes,  20  grams  of  finely  powdered 
aluminium  chloride.  (See  16,  p.  59.)  The  chloride  should  be 
exposed  to  the  air  as  little  as  possible.  Connect  with  a  reversed 
condenser,  and  heat  on  the  water-bath  for  two  to  three  hours, 
or  till  the  evolution  of  hydrochloric  acid  nearly  ceases.  Distil 
oft"  the  carbon  disulphide,  and  pour  the  residue  into  300  cc.  of 
water  in  a  flask,  cooling,  if  necessary.  Add  10  cc.  of  concentrated 
hydrochloric  acid,  and  pass  a  rapid  current  of  steam  through  the 
liquid  foe  a  short  time  to  expel  the  rest  of  the  benzene  and  carbon 
disulphide.  Collect  the  benzophenone  with  some  ether,  separate, 


IO2  ORGANIC    CHEMISTRY 

wash  the  ethereal  solution  by  shaking  it  several  times  with  water, 
and  with  a  solution  of  sodium  hydroxide,  dry  it  with  calcium 
chloride,  and  fraction  the  residue,  after  distilling  off  the  ether, 
using  a  distilling  bulb,  and  collecting  the  distillate  directly  m  a 
test-tube,  or  preparation  tube,  without  using  a  condenser.  Yield 
20  to  21  grams. 

Benzophenone  melts  at  48.5°,  and  boils  at 

303.7°  under  723.05  mm. 

304.5°  73545  " 

305.50       "       750.91  " 
306.1°       "       760.32  " 

306.4°       "       765-06  " 
This  table  is  of  especial  value  for  testing  thermometers.     (See 

P.  28.) 

When  benzophenone  is  warmed  with  hydroxylamine  hydro- 
chloride,  caustic  soda  in  excess,  and  alcohol,  for  two  hours,  an 
oxime  melting  at  140°  is  formed.  If  this  oxime  dissolved  in  dry 
ether,  is  treated  successively  with  one  and  a  half  times  its  weight 
of  phosphorus  pentachloride,  and  with  water,  it  is  converted  into 
benzanilide  (Beckmann's  rearrangement). 
C6H5  -  C  —  C6H5  +  PC15  :  C,,H5  -  C  —  C6H5  +  POC1,  -f  HC1 

II  II 

NOH  N  —  Cl 

C6H5 .—  C  —  C6H6  C6H5  -  C  -  Cl 

II  II 

N  —  Cl  N  —  C6H5 

C6H5  —  C  -  Cl  +  H20  C5H5  -  C  =  O 

II  I  +  HC1. 

N  —  C6H5  HN  -  C6H5 

The  study  of  this  reaction  has  been  of  great  value  in  the  devel- 
opment of  theories  about  the  stereochemistry  of  nitrogen.  Un- 
symmetrical  oximes  which  occur  in  two  forms,  as,  for  instance, 
monobrombenzophenone  oxime,  C6H4BrCC6H5,  may  be  rearraug- 

II 
NOH 

ed  in  this  manner,  and  each  form  gives  a  different  product :  viz., 
brombenzoylanilide  and  benzoylbromanilide. 


ALDEHYDES,    KETONES    AND   THEIR    DERIVATIVES  103 

C6H4Br  —  C  —  C6H5  —  C6H4BrCONHC6H5. 

II 
.     NCI 

C6H4Br  -  C  -  C6H5  —  C6H5CONHC6H4Br. 

II 
Cl  —  N 

The  two  compounds  can  be  distinguished  by  their  saponifica- 
tion  products. 

42.  Oxidation  of  a  Hydrocarbon  to  a  Quinone. — Anthraquin- 

/C0\ 
one,   C.H/        )>C6H4. 

XCCX 

Literature — Laurent,  Berzelius :  Jahresb.,  16,  366 ;  Anderson :  Ann.,  122, 
301;  Kekule,  Franchimont :  Ber.,  5,  908;  Ullmann :  Ann.,  291,  24;  W.  H. 
Perkin,  Jr. :  J.  Chem.  Soc.,  59>  1012 ;  Graebe,  Liebermann :  Ann.  Supl.,  7» 
285. 

10  grams  anthracene. 

17  grams   chromic  anhydride. 

100  cc.  glacial  acetic  acid. 

Put  10  grams  of  anthracene,  and  75  cc.  glacial  acetic  acid  in  a 
flask  connected  with  an  upright  condenser,  heat  to  boiling,  and 
add,  slowly,  17  grams  of  chromic  anhydride,  dissolved  in  the 
smallest  possible  amount  of  water,  and  the  solution  diluted  with 
25  cc.  glacial  acetic  acid.  Boil  for  five  to  ten  minutes,  pour  the 
solution  into  water,  filter,  and  wash.  Dry  the  residue,  and  crys- 
tallize it  from  glacial  acetic  acid,  or  from  toluene.  It  may  also 
be  purified  by  sublimation  (see  p.  ..).  Yield  almost  quantita- 
tive, if  the  anthracene  is  pure. 

Anthraquinone  sublimes  -in  yellow  needles,  which  melt  at 
273°,  and  boil  at  379°-38i°.  100  parts  of  toluene  dissolve  0.19 
parts  at  15°,  and  2.56  parts  at  100°.  By  distilling  with  zinc  dust 
anthracene  is  regenerated. 

43.  Preparation  of  a  Derivative  of  a  Ketone  by  Condensation 
of  Phthalic  Anhydride  with  a  Hydrocarbon. — Orthobenzoylbenzoic 

/CO-C6H5 

Acid,  C6H4^  ,  Diphenylmethanonemethjllic  (2)  acid. 

XC02H 


IO4  ORGANIC    CHEMISTRY 

Literature — Plaskuda,  Zincke  :  Ber.,  6,  707 ;  Behr,  vanDorp  :  Ibid,  7>  i? ; 
Friedel,  Crafts:  Ann.  chim.  phys.  [6],  14,  446;  Pechmann :  Ber.,  13*  1612; 
Graebe  and  Ullmann :  Ann.,  291,  8. 

20  grams   phthalic   anhydride. 

100  cc.  benzene  (free  from  thiophene). 

30  grams  aluminium  chloride. 

In  a  300  cc.  flask  put  20  grams  of  phthalic  anhydride,  and 
100  cc.  of  benzene,  free  from  thiophene.  Warm  till  the  anhydride 
dissolves,  and  cool.  Connect  with  an  upright  condenser,  and 
add,  in  portions  of  3-5  grams,  30  grams  of  dry,  powdered  alu- 
minium chloride.  If  the  reaction  becomes  too  violent,  cool  the 
flask  with  water.  The  whole  of  the  chloride  may  be  added  in 
ten  to  fifteen  minutes.  Warm  on  the  water-bath  for  two  hours. 
Cool,  add  carefully,  through  the  condenser,  80  cc.  of  cold  water, 
and  20  cc.  of  concentrated  hydrochloric  acid.  Distil  off  the  ben- 
zene with  water  vapor,  cool,  filter,  and  wash.  Dissolve  the 
acid  in  80  cc.  of  a  lO-per  cent.,  solution  of  sodium  carbonate, 
filter,  and  pour  into  a  mixture  of  35  cc.  of  concentrated  hydro- 
chloric acid,  40  cc.  of  water,  and  some  pieces  of  ice.  Filter, 
and  suck  dry  on  a  plate  (p.  120).  In  order  to  obtain  the  dry  o- 

/CO-C.H, 

benzoylbenzoic  acid,  C6H4<^  ,  this  product  may  be  clried 

\CO2H 

at  I25°-I3O°,  or  it  may  be  dissolved  in  warm  chloroform,  sep- 
arated from  the  water  swimming  on  top,  the  solution  dried  with 
calcium  chloride,  and  the  chloroform  distilled.  The  dry  acid 
may  be  crystallized  from  xylene.  Yield  22  to  23  grams. 

Orthobenzoylbenzoic  acid  crystallizes  from  water  in  long  nee- 
dles, which  contain  water  of  crystallization  and  melt  at  85°- 
87°.  It  is  moderately  soluble  in  hot  water,  difficultly  soluble  in 
cold  water. 

When  the  dry  acid  is  heated  to  200°,  for  an  hour,  with  an 
equal  weight  of  phosphorus  pentachloride,  it  is  converted  al- 
most quantitatively  into  anthraquinone. 


ALDEHYDES,     KETONES    AND    THEIR    DERIVATIVES  IO5 

44.  Preparation  of  a  Ketone  Ether  by  the  Condensing  Action 

xCOv 

of  Sulphuric  Acid.—  Xanthone,    C6H/         /C6H4. 

\0/ 

Literature — Preparation  by  the-  oxidation  o.f  methylene  diphenylene- 
ketone  oxide,  Mertz,  Weith :  Ber.,  14*  192;  From  2.2'diaminobenzo- 
phenone  with  nitrous  acid,  Staedel :  Ann.,  283,  175 ;  From  salicylic  acid 
and  acetic  anhydride,  W.  H.  Perkin :  Ber.,  16,  339 ;  Richard  Meyer  and 
Hoffmeyer :  Ber.,  25,  2118;  By  warming  salicylic  phenyl  ether  with  sul- 
phuric acid,  Graebe :  Ber.,  21,  503. 

3  grams  phenyl  ether  of  salicyclic  acid. 
20  cc.  concentrated  sulphuric  acid. 

Put  3  grams  of  the  phenyl  ether  of  salicyclic  acid  (31,  p.  84) 
and  20  cc.  of  concentrated  sulphuric  acid  in  a  small  flask,  heat 
for  half  an  hour  on  the  water-bath,  cool,  pour  into  about  200 
cc.  of  water,  filter  off  and  wash  the  precipitated  xanthone  and 
recrystallize  it  from  hot  alcohol,  or,  after  drying,  from  benzene. 
Xanthone  crystallizes  in  needles  which  melt  at  I73°-I74°.  If 
dissolves  in  concentrated  sulphuric  acid  with  a  yellow  color  and 
intensive  blue  fluorescence.  'It  may  be  readily  converted  into 

C6H5 

/C(OH)v 

phenyl  xanthenol,    C6H/  /C6H4,   by  the  Barbier-Grig- 

\0 / 

nard  reaction,  Gomberg  and  Cone:  Ann.,  370.  173.     (See  also  p. 
74.) 

Instead  of  concentrated  sulphuric  acid  phosphorus  pentachlo- 
ride  (to  form  the  acid  chloride)  followed  by  aluminium  chlo- 
ride, (see  41,  p.  101)  may  be  used.  For  naphthalene  derivatives 
this  is  essential  because  of  the  ease  with  which  they  are  sul- 
phonated.  Ullmann :  Ann.,  355,  349. 


Chapter  VII 

ACIDS 

I.  Oxidation  of  Alcohols,  Aldehydes,  Ketones,  and  Hydro- 
carbons.-— The  oxidation  is  usually  effected  by  a  mixture  of  po- 
tassium pyrochromate,  sulphuric  acid,  and  water,  by  dilute  nitric 
acid,  or  by  potassium  permanganate  in  alkaline  solution. 

With  the  chromic  acid  mixture  the  first  product  of  the  oxida- 
.tion  of  an  alcohol  is  probably  an  aldehyde  or  ketone.  In  the 
case  of  ethyl  alcohol  the  aldehyde  is  so  volatile  as  to  escape 
rapidly  as  soon  as  formed  and  the  method  cannot  be  practically 
used  for  the  preparation  of  acetic  acid. 

With  some  of  the  higher  alcohols  of  the  same  series  the  acid 
which  is  formed  by  the  oxidation  of  a  part  of  the  alcohol  com- 
bines with  another  portion  of  the  alcohol  to  form  a*n  ester.  The 
continued  action  of  the  oxidizing  mixture  may  saponify  the  ester 
and  complete  the  oxidation  of  the  alcohol,  but  it  is  sometimes 
better  to  moderate  its  action  so  that  the  ester  is  the  chief  product 
of  the  oxidation  and  to  secure  the  acid  by  the  saponification 
of  the  latter  (isovaleric  acid). 

The  oxidation  of  open  chain  ketones  and  of  secondary  alcohols 
can  give  rise  to  the  formation  of  acids  only  by  separating  the 
molecule  into  two  parts.  The  carbonyl  of  the  ket'one  usually, 
but  not  always,  goes  with  the  smaller  part.  There  may  result 
a  single  acid,  as  in  the  case  of  methyl  ethyl  ketone  (2-butanone), 
or  two  acids,  as  with  dipropyl  ketone  (4-heptanone  or  propyl 
methyl  ketone  (2-pentanone).  In  the  latter  case,  for  purposes 
of  investigation,  the  separation  of  homologous  fatty  acids  be- 
comes important.  This  can  be  effected  by  distilling  an  aqueous 
solution  of  the  acids.  The  acid  of  higher  molecular  weight 
passes  over  first  with  the  water  vapor,  apparently  because  it  is 
less  soluble  in  water  and  because  of  its  lower  ionization  constant, 
as  the  portion  of  an  acid  which  is  ionized  can  pass  over  only 
to  a  trifling  extent,  if  at  all,  with  steam.  By  preparing  silver 


AQIDS  107 

i 

salts  of  the  acids  in  the  first  and  last  portions  of  the  distillate 
the  composition  of  the  acids  formed  cah  be  established.  (See 
47,  p.  119),  separation  of  propionic  and  butyric  acids.) 

The  oxidation  of  cyclic  ketones,  and  in  some  cases  of  other 
cyclic  compounds,  gives  rise  to  the  formation  of  bi-basic  acids 
(camphoric  acid). 

In  the  benzene  series,  a  side  chain  consisting  of  allyl  (CH3, 
C2H5,  etc.)  or  another  group  in  which  a  carbon  atom  is  com- 
bined directly  with  the  benzene  nucleus,  can  be  oxidized  to  car- 
boxyl.  In  the  case  of  hydrocarbons,  the  oxidation  is  usually 
effected  with  difficulty,  partly  owing  to  their  insolubility  in  the 
oxidizing  agents  employed.  On  this  account  it  is  sometimes  ad- 
visable to  prepare,  at  first,  a  halogen  derivative  having  the  halo- 
gen in  the  side  chain  (Baeyer:  Oxidation  of  paraxylene,  Ann. 
245,  138;  benzoic  acid,  p.  125). 

In  a  similar  manner  an  acetyl  group,  COCH3,  may  be  con- 
verted to  the  group  COCH2Br  by  treatment  with  bromine  in  a 
solution  in  carbon  bisulphide  and  the  latter  may  be  oxidized 
to  the  glyoxylic  group,  COCO2H,  by  shaking  with  a  cold,  5  per 
cent,  solution  of  potassium  permanganate.  (Verley:  Bull.  soc. 
chim.,  17,  906.)  The  glyoxylic  group  is  converted  into  the  alde- 
hyde group,  in  some  cases,  by  heat  (p.  88)  or  it  may  be  oxidized 
to  carboxyl  by  means  of  manganese  dioxide  and  sulphuric  acid. 

The  acetyl  group  may  be  oxidized  to  carboxyl  with  the  simul- 
taneous formation  of  chloroform  or  bromoform  by  means  of  so- 
dium hypochlorite  or  hypobromite.  (See  39,  p.  99.) 

II.  Saponification  of  Cyanides. — The  cyanides  of  organic  radi- 
cals, or  "nitriles"  of  acids,  may  be  obtained  from  halogen  de- 
rivatives of  hydrocarbons,  salts  of  acid  sulphuric  esters  of  alco- 
hols, or  salts  of  sulphonic  acids  by  treating  with  potassium 
cyanide.  The  last  two  cases  are  applicable  only  when  the  cy- 
anide formed  can  be  distilled  from  the  dry  mixture  without  de- 
composition. 

Nef  has  shown  that  potassium  cyanide  has  the  structure  K — 
N  =  C,  and  the  reaction  probably  takes  place  in  two  stages : 


IO8  ORGANIC    CHEMISTRY 

» 

ci 


K  —  N  =  e       RC1  K 


/ 

--N=CC 


L\  R\  x° 

>C  =  O  +  HCN  =       >C< 
¥  R/      XC 


N  =  C  —  R  -h  KC1. 

A  small  amount  of  an  isocyanide  is  formed  at  the  same  time, 
the  group  r  -  N  =  C  taking  the  place  of  the  halogen  or  acid 
group  of  the  organic  compound. 

Cyanhydrines,  which  by  saponification  give  a-hydroxy  acids, 
can  be  prepared  by  treating  aldehydes  or  ketones  with  hydrocy- 
anic acid,  best  in  the  nascent  state: 

,OH 

R/  R/       NCN 

From  aromatic  amines  cyanides  can  be  obtained  by  treating  a 
diazonium  salt  with  cuprous  cyanide.  (Sandmeyer.) 

R  —  NH.HC1  +  HN02  ==  R  -    N  =  N  4   2H2O, 

Cl 
2R  —  N  =  N  +  Cu2C2N2  =  2R  --  CN  -f  Cu2Cl2. 

Cl 

The  cuprous  cyanide  for  the  reaction  is  prepared  from  copper 
sulphate. 

CuSO4  +  2KCN   :  :   Cu(CN)2  +  K2SO4, 
2Cu(CN)2t=  Cu2(CN)2  +  (CN)2. 

The  saponification  of  cyanides  is  usually  effected  either  by 
the  action  of  an  aqueous  or  alcoholic  solution  of  potassium,  so- 
dium, or  barium  hydroxide,  or  by  the  action  of  hydrochloric  or 
sulphuric  acid.  An  amide  of  the  organic  acid  is  probably  always 
an  intermediate  product  of  the  saponification  and,  in  some  cases, 
the  conversion  of  the  cyanida  into  an  amide  and  the  conversion 
of  the  latter  into  the  acid  may,  with  advantage,  be  carried  out 
in  two  stages  and  by  means  of  different  agents. 

O 
R  _  c  =  N  +  H2O  =  R  —  C  —  NH2, 


ACIDS  IO9 

O  O 

R  _.  C  —  NH2  4-  KOH  ==  RC  —  OK  -r-   NH2,  or 
O  O 

R  -  C  —  NH,  +  H20  +  HC1  =  RC  -  OH  -f  NH4C1. 

III.  Condensation. — By  condensation,  in  general,  is  meant  the 
formation  of  a  compound  from  two  others  with  the  elimination 
of  water,  alcohol,  ammonia,  hydrochloric  acid,  or  two  halogen 
atoms.1  Methods  of  condensation  have  been  especially  useful 
in  the  synthesis  of  acetoacetic  ester  and  its  derivatives,  of  cinna- 
mic  acid,  and  of  many  other  compounds  in  which  the  same  prin- 
ciples have  been  applied. 

In  the  case  of  acetoacetic  ester  the  condensation  appears  to 
take  place  as  follows : 

CH3CO.|OC2H5T  H|CH3CO2C2H5  =  CH3COCH2CO2C2H5 
-f  C2H5OH. 

The  researches  of  Claisen  indicate,  however,  that  the  action 
consists,  at  first,  in  the  addition  of  sodium  ethylate,  formed  from 
a  trace  of  alcohol  which  is  always  present  in  acetic  ester,  to  the 
ester,  thus: 


-h  NaOC2H5  ^  CH3  —  C-OC2H5. 

\OC2H5 

The  addition  product  then  condenses  with  a  second  molecule 
t)f  acetic  ester  thus: 

.ONa 

CH3—  C— !OC2H5       HJCH.CO2C2H5  = 
\JOC2H5 

ONa 

CH3  —  C  =  CH.CO2C2H5  +  2C2H5OH. 

1  Some  authors  use  the  term  condensation  exclusively  as  applied  to  reactions  in  which 
carbon  atoms  unite,  and  especially  with  the  elimination  of  water  or  alcohol,  but  there 
appears  to  be  no  logical  reason  for  such  a  restriction  in  its  use. 


HO  ORGANIC    CHEMISTRY 

According  to  this  view,  on  the  addition  of  an  acid  a  compound 

OH 

/ 

of  the  formula  CH3  —  C  =  CH  —  CO2C2H5  would  be  liberated. 

A  very  large  amount  of  work  has  been  done  for  the  purpose 
of  discovering  whether  acetoacetic  ester  and  similar  compounds 
have  the  "enol"  (unsaturated  alcoholic)  or  ketone  structure. 
It  would  seem  that  substances  of  this  character  pass  very  readily 
from  one  form  into  the  other  and  that  while,  in  some  cases, 
they  may  consist  exclusively  of  the  one  or  the  other  form,  in 
others  they  are,  in  all  probability,  mixtures  of  the  two  forms. 
Therefore  the  compounds  in  question  may  react  in  one  or  the 
other  form  or  in  both,  according  to  the  reagents  used,  one  form 
passing  over  into  the  other,  as  the  one  or  other  form  disappears 
in  the  progress  of  the  reaction. 

Very  closely  analogous  to  the  preparation  of  acetoacetic  ester 
is  the  preparation  of  succinylosuccinic  ester  by  the  condensation 
of  succinic  ester. 

COAH, 

NaO  CO.C.H.  | 

\    i  ......  or  H  ...........  ?  I  Na°       C 


I  I        -  !  |  C      CH, 

CH2  CH,  —  || 

I  I  ...........  c  i'S      !  CH*     C-ONa 

C:H2     pSHSXi>C—  ONa  \// 

I    j  V-SnSl-'i  Q 

CO,C,H,  ......  I 

CO.C.H, 

Succinic  ester  +  sodium  ethylate.  Sodium  salt  of  succinyl- 

osuccinic ester. 

By  the  action  of  sodium  ethylate  on  a  mixture  of  esters  or  of 
esters  and  ketones  or  aldehydes,  many  similar  condensations 
may  be  effected.  In  every  case  one  ester  group,  after  adding 
sodium  ethylate,  condenses  with  a  methyl  or  methylene  group 
which  is  adjacent  to  the  carbonyl  of  a  ketone  or  of  an  ester 
group.  That  the  methin  group  (CH)  is  not  susceptible  to  this 
sort  of  condensation  is  one  of  the  proofs  for  Claisen's  view,  re- 
ferred to  above  (Ber.,  20,  651  ;  21,  1154). 


ACIDS  I I I 

Acetoacetic  ester  and  similar  compounds  which  contain  a 
methylene  or  methin  group  between  two  carbonyl  or  ester  groups 
give  sodium  salts  when  treated '  with  sodium  ethylate.  In  some 
cases  cyanogen  or  other  groups  may  have  the  same  effect  as  car- 
bonyl. According  to  the  view  now  most  generally  held,  the  so- 
dium is  combined  with  oxygen  in  these  sodium  salts  ("enol" 
form,  see  above),  though  some  chemists  formerly  supposed  that 
it  is  combined  with  carbon  (ketone  form).  When  these  sodium, 
silver,  or  copper  salts  of  acetoacetic  ester,  malonic  ester,  and 
similar  compounds  are  treated  with  alkyl  iodides,  acid  chlorides, 
or  other  halogen  derivatives,  compounds  are  formed  in  which 
the  alkyl  or  other  groups  are  sometimes  combined  with  carbon 
and  sometimes  with  oxygen. 
ONa 

CH3  —  C  =  CH  —  C02C2H5  -f  CH3I  - 
ONa  CH3 

/       / 

CH,  -  CI  -  CH  -'  CO,C,H6'  = 

CH. 

CH3  -  CO  -  CH  -  C02C2H5+  Nal, 

Ocu 

/ 
CH3  —  CH  ==  CH-  CO2C2H.  +  CH3COC1  - 

O  —  COCH3 

CH3  —  C  =  CH  —  C02C2H5  +  cuCl.1 
(See  Nef :  Ann.,266,  103,  no,  and  287,  270.) 

With  alkyl  iodides,  compounds  -containing  the  alkyl  com- 
bined with  carbon  are  almost  exclusively  formed. 

This  method  has  been  of  very  great  value  in  obtaining  deriva- 
tives of  acetoacetic  ester,  CH3COCH2CO2C2H5,  malonic  ester, 

/CO.C.H. 
CH./  ,  and  other  compounds. 

\CO,C,H. 

1  In  this  case  "  cu  "  is  used  to  represent  an  equivalent  instead  of  an  atom  of  copper. 


112  ORGANIC    CHEMISTRY 

Acetoacetic  acid  and  almost  all  other  /?-ketonic  acids  are  ex- 
tremely unstable  in  the  free  state.  Hence,  if  the  esters  of  these 
acids  are  saponified,  decomposition  products  are  usually  obtained 
instead  of  the  free  acid.  These  products  vary  according  to  the 
nature  of  the  ester  and  the  means  used  for  its  saponification. 
In  general,  saponification  with  acids  causes  decomposition  with 
loss  of  carbon  dioxide  and  formation  of  a  ketone  (ketorric 
decomposition)  : 

CH3COCH,CO2CaH3  -f-  H2SO4  -f  H2O  = 

Acetoacetic  ester 

CH:JCOCH3   +  C2Hr,OH  -p   H2SO4  +  CO2. 

Acetone 

(See  also  Baeyer:  Ann.,  278,  90,  for  the  saponification  of  suc- 
cinylosuccinic  ester.) 

Saponification  with  strong  bases,  on  the  other  hand,  tends  to 
favor  the  formation  of  acids   (acid  decomposition). 
CHSCOCH2CO,C2H,  -}-  2KOH  :  =  CH3CO2K  +  CH:!CO,K 

Hh  C,H,OH. 

Free  malonic  acid  and  its  derivatives,  that  is,  all  compounds 
having  two  carboxyls  combined  with  the  same  carbon  atom,  al- 
though stable  at  ordinary  temperatures,  are  decomposed  when 
heated  to  I5O°-2OO°,  and  many  of  them,  also,  when  heated  with 
moderately  strong,  not  concentrated,  sulphuric  acid.  The  value 
of  acetoacetic  ester  for  synthetic  purposes  is  lessened  because  of 
the  difficulty  of  securing  a  clean  "acid  decomposition"  and,  since 
the  same  product  may  usually  be  obtained  by  the  use  of  malonic 
ester,  the  latter  is  now  more  frequently  used  in  syntheses. 

/C02C2H5 
Cyanacetic  ester,    CH2\  ,  may  be  condensed  with  alkyl 

XCN 

halides  by  the  same  methods  used  for  malonic  ester  and  it  seme- 
times  gives  normal  products  when  malonic  ester  fails  to  do  this. 
Thus  it  may  be  used  to  prepare  trimethyl  succinic  acid  from 
bromoisobutyric  ester,  (CH8)aCBrCO2C2H5,  while  malonic  ester 
gives  methyl  glutaric  ester  as  the  chief  product.  (Bone  and 
Spranklin :  J.  Chem.  Soc.,  75,  854 ;  Noyes :  Am.  Chem.  J.,  33, 

358.) 


ACIDS  113 

In  some  cases  the  sodium  compound  of  malonic  ester  may  be 
prepared  and  used  in  a  toluene  solution  to  advantage  and  in 
others  it  is  well  to  employ  magnesium  ethylate  prepared  by  the 
use  of  magnesium  amalgam  in  alcoholic  solution.  (Noyes  and 
Kyriakides:  J.  Am.  Chem.  Soc.,  32,  1058.) 

Another  method  of  condensation  used  for  the  preparation  of 
acids,  known  as  Perkin's  synthesis  (Perkin:  Ann.  147,  230;  Ber., 
8,  1599;  Jahresb.,  /#//,  789;  Tiemann,  Herzfeld:  Ber.,  10,  68), 
consists  in  heating  a  mixture  of  an  aldehyde,  a  sodium  salt,  and 
acetic  anhydride.  One  of  the  most  common  illustrations  is  the 
synthesis  of  cinnamic  acid,  which  appears  to  take  place  as  fol- 
lows : 

C6H5CH;0  "+  H2;CHC02Na  =,  C.H6CH=CHCO,Na  +  H2O. 

Benzaldehyde  Sodium  cinnamate 

The  reaction  has  been  shown  lo  take  place  in  two  stages  and 
consists,  first,  in  an  addition  of  the  sodium  salt  to  the  aldehyde 
gro.-.p- 


O 
C6H.C^      -f    HCH.,CO2Na  =  C6H.C-CH2CO2Na. 

'  \H          -  •  \H 

This  addition  is  followed,  under  the  influence  of  the  acetic 
anhydride,  by  loss  of  water.  The  addition  always  takes  [..lace 
\viih  the  methyl,  methylene  or  methin  group  adjacent  to  the 
carboxyl.  Unlike  the  acetoacetic  ester  syntheses,  the  addition 
may  take  place  with  a  methin  group  as  well  as  with  methyl  and 
methylene  groups,  but  in  that  case  there  can  be  no  loss  of  water, 
and  a  hydroxy  acid  is  formed.  This  is  one  of  the  most  im- 
portant proofs  that  the  course  of  the  reaction  is  as  given.  His- 
torically this  reaction  was  first  used  in  the  synthesis  of  cumarin 
by  Perkin.  Later,  cinnamic  acid  and  its  derivatives  became  of 
especial  interest  because  of  -their  use  by  Baeyer  in  the  synthesis 
of  indigo. 

Knoevenagel  (Ber.,  27,  2345;  Ann.,  281,  104)  discovered  a 
similar  synthesis  in  which  formaldehyde  is  used,  and  condensa- 


114  ORGANIC   CHEMISTRY 

tion  takes  place  under  the  influence  of  some  organic  base.     The 
mechanism   of  the   reaction    is   not   clearly   understood. 

Another  similar  condensation,  but  one  which  does  not  lead 
to  the  formation  of  an  acid,  is  that  of  formaldehyde,  with  de- 
rivatives of  benzene  and  its  homologues,  under  the  influence  of 
concentrated'  sulphuric  acid. 

N02 

2C6H5N02  +  CH20  =  C6H4  —  CH2  —  C6H4  —  NO2  +  H2O. 

(Schopff:  Ber.,  27,  2321.) 

IV.  Decomposition  of  Bibasic  Acids. — This  method  of  prep- 
aration is  used  in  connection  with  the  synthesis  by  condensa- 
tion of  derivatives  of  malonic  acid.  In  the  case  of  acids  where 
the  two  carboxyl  groups  are  not  combined  with  the  same  car- 
bon atom,  a  clean  decomposition  cannot  usually  be  effected  by 
heat  alone.  In  some  cases,  however,  one  of  the  carboxyls  may 
be  removed  by  heating  the  barium  salt  of  a  bibasic  acid  with 
sodium  methylate  (Mai:  Ber.,  22,  2136). 

The  decomposition  of  oxalic  acid  may  be  considered  as  a 
special  case  under  this  head: 

CO,H 

=  HCO.H  -f  C02. 
CO,H 

The  decomposition  effected  by  heat  alone  is  unsatisfactory 
in  this  case,  also,  and  heating  with  glycerol  is  practically  used. 

xOCHO 

The  glycerol   appears  to  form    an    ester,    C3H5<  ,  with 

\OH), 

the  formic  acid  as  it  is  formed.  This  ester  then  decomposes 
with  the  water  present,  yielding  formic  acid  and  regenerating 
the  glycerol. 

V.  Preparation  from  Natural  Products. — Many  acids,  as  stear- 
ic,   oleic,   succinic,   benzoic  and   others,   occur   in   nature   in   the 
form  of  esters  or  glucosides,  and  may  be  obtained  from  these 
by  saponification  or  decomposition  by  acids  or  alkalies. 
(C17H3r,C02)3.C3H5  +  3KOH  =  3C1TH,.COtK  +  C8H5(OH),. 

Stearin  Potassium  stearate  +  Glycerol 


ACIDS  115 

The  preparation  of  acids  by  oxidation  of  other  compounds 
has  already  been  referred  to.  Many  other  illustrations  of  the 
preparation  of  acids  from  natural  products  might  be  given, 
but  most  of  these  are  individual  rather  than  general,  and  their 
discussion  would  be  out  of  place  here. 


45.  Preparation  of  Acids  by  Decomposition  of  Bibasic  Acids. 

— Formic  acid,  H.CO3H.     (Methanoic  acid.) 

Literature — Berthelot:  Ann.  chim.  phys.  [3],  46,  477;  Ann.,  98,  139; 
Seekamp:  Ibid,  122,  113;  Lorin :  Ann.  chim.  phys.,  [4],  29,  367;  Romburgh: 
Compt.  rend.,  93,  847;  Roscoe :  Ann.,  125,  320;  Maquenne:  Bull,  soc, 
chim.,  [2],  50,  662;  Liebig:  Ann.,  17,  69. 

50  grams  glycerol. 
50  grams  oxalic  acid. 

Place  in  a  150  cc.  distilling  bulb  50  grams  of  glycerol,  and 
50  grams  of  crystallized  oxalic  acid.  Insert  a  thermometer,  im- 
mersed in  the  liquid.  Connect  with  a  condenser,  and  heat  with 
a  low  flame  till  the  thermometer  rises  slowly  to  105°.  Allow  to 
cool  to  about  50°,  add  50  grams  more  of  oxalic  acid  and  distil 
again,  always  over  a  low  flame  and  slowly  till  a  temperature  of 
115°  is  shown  by  the  thermometer.  Repeat  almost  indefinitely, 
distilling  to  a  temperature  of  H5°-I25°.  The  acid  coming  over 
in  the  later  distillations  will  be  stronger  than  that  of  the  first. 
The  residue  may  be  used  for  the  preparation  of  allyl  alcohol 
(see  21,  p.  69). 

Pure  formic  acid  cannot  be  obtained  from  the  dilute  acid  by 
distillation,  the  tendency  being  for  a  dilute  acid  to  become  more 
concentrated,  or  a  concentrated  acid  weaker  by  distillation,  till 
an  acid  boiling  at  107°  and  of  77  per  cent,  finally  passes  over. 
Weaker  acids  may  be  concentrated  to  this  strength  by  distillation. 
A  nearly  anhydrous  acid  can  then  be  obtained  by  dissolving  an- 
hydrous oxalic  acid  in  this  acid  with  the  aid  of  heat,  in  such 
amount  that  on  crystallizing  with  two  molecules  of  water  it  will 
somewhat  more  than  combine  with  all  of  the  water  present. 
After  the  oxalic  acid  has  crystallized,  the  formic  acid  is  poured 
off  and  distilled. 


U6  ORGANIC    CHEMISTRY 

An  anhydrous  acid  may  also  be  obtained  by  the  decomposition 
of  the  lead  salt  with  hydrogen  sulphide. 

Formic  acid  melts  at  8.3°,  boils  at  101°,  and  has  a  specific 
gravity  of  1.2256  at  15°.  The  lead  salt,  which  is  easily  prepared 
by  dissolving  lead  carbonate  in  the  hot  dilute  acid,  is  the  most 
characteristic.  It  dissolves  in  5^/2  parts  of  hot  water,  and  in 
63  parts  of  water  at  16°.  The  copper  salt  also  crystallizes  well. 

When  heated  with  concentrated  sulphuric  acid,  formic  acid 
decomposes  into  water  and  carbon  monoxide.  On  warming,  it 
reduces  solutions  of  silver  salts  with  the  separation  of  metallic 
silver.  On  warming  with  mercuric  chloride  calomel  separates. 
On  heating  the  sodium  salt  with  caustic  soda,  hydrogen  is  lib- 
erated. 

The  specific  gravity  of  the  dilute  acid  is  as  follows: 

Per  cent.  CH2O2  Specific  gravity  at  15° 
10  .025 

30  .080 

50  .124 

70  .l6l 

ioo  .223 

46.  Preparation   of   an   Acid  by   Oxidation   of   an   Alcohol. — 

Isovaleric  acid   (3-methylbutanoic  acid). 

CH3, 

>CH.CH2C02H. 
CH/ 

Literature — Dumas  u.  Sfras :  Ann.,  33,  156;  35,  143;  Pierre  and 
Puchot:  Ann.  chim.  phys.,  [4],  29,  229;  Stalmann :  Ann.,  147,  129;  Er- 
lenmeyer  u.  Hell:  Ibid,  160,  275;  Duclaux :  Compt.  rend.,  105,  171. 

ioo  cc.  amyl  alcohol  (3-methyl  butanol). 

ioo  grams  sodium  pyrochromate.1. 

200   cc.   water. 

90  cc.  concentrated  sulphuric  acid. 

90  cc.  water. 

In  a  one  liter  flask  place  ioo  cc.  amyl  alcohol  (fusel  oil),  ioo 
grams  of  powdered  sodium  pyrochromate,  and  200  cc.  of  water. 
Place  in  the  mouth  of  the  flask  a  stopper  bearing  a  small,  up- 

1  The  use  of  sodium  rather  than  potassium  pyrochromate  is  advised  in  this  and  other 
cases  because  of  the  greater  solubility  of  the  salt. 


ACIDS  117 

right  condenser  having  a  rather  wide  tube.  (Fig.  24,  p.  68.) 
Add  in  small  portions,  through  the  condenser  tube,  a  cooled  mix- 
ture of  90  cc.  of  concentrated  sulphuric  acid  and  90  cc.  water. 
Shake  vigorously  and  take  care  that  the  addition  of  the  acid  is 
so  regulated  that  the  reaction  does  not  become  too  violent.  The 
flask  may  be  cooled  occasionally  by  setting  it  in  cold  water,  if 
necessary. 

When  the  acid  has  all  been  added  and  the  mixture  no  longer 
tends  to  grow  warm  when  shaken,  remove  the  condenser  and  re- 
place- it  by  a  stopper  bearing  two  glass  tubes,  one  reaching  near- 
ly to  the  bottom  of  the  flask,  and  the  other  a  short  bent  tube 
leading  to  a  condenser  as  shown  in  Fig.  23,  p.  71.  Distil  by 
passing  into  the  flask  a  rapid  current  of  steam. 

The  oxidation  converts  a  part  of  the  amyl  alcohol  into  valeric 
acid,  which  then  combines  with  another  part  of  the  alcohol  to 
form  an  ester. 

The  distillation  should  be  continued  as  long  as  the  ester  con- 
tinues to  come  over.  Separate  the  ester  from  the  aqueous  solu- 
tion, by  means  of  a  separatory  funnel,  saving  both.  Put  the 
ester  into  a  500  cc.  flask  with  60  cc.  of  the  aqueous  solution  and 
30  grams  of  solid  caustic  soda.  Adjust  an  upright  condenser, 
as  before,  and  boil  gently  for  fifteen  minutes,  placing  the  flask 
on  a  thin  asbestos  board  or  on  a  wire  gauze  covered  with  a  thin 
sheet  of  asbestos  paper.  Then  add  the  remainder  of  the  aqueous 
solution,  which  contains  some  valeric  acid,  and  distil,  either  di- 
rectly or  with  steam  as  long  as  amyl  alcohol  comes  over.  The 
amyl  alcohol,  which  is  recovered,  may  be  saved  for  use  in  a  new 
oxidation.  Concentrate  the  residue  in  the  distilling  flask  to 
about  100  cc.  by  evaporation  in  a  porcelain  dish.  Transfer  to  a 
flask,  cool,  and  add  50  cc.  of  dilute  sulphuric  acid  (1:1  by  vol- 
ume). Separate  the  valeric  acid  by  means  of  a  separatory  fun- 
nel, drawing  off  the  solution  below  and  pouring  the  acid  out  of 
the  top  of  the  funnel  into  a  dry,  50  cc.  flask.  Add  5  grams  of 
fused  calcium  chloride,  stopper  loosely  and  warm  for  ten  min- 
utes on  a  water-bath.  Cool,  pour  off  the  acid  into  a  small  dis- 


Il8  ORGANIC    CHEMISTRY 

tilling  bulb  and  distil,  using  a  thermometer  and  an  air  condenser 
(See  Fig.  n,  p.  26.)  Collect  in  dry  test-tubes  the  fractions: 
below  168°,  i68°-i78°  and  I78°-I9O°.  Clean  the  distilling  bulb 
and  put  in  the  low  boiling  fraction  and  distil  till  the  thermometer 
reaches  170°,  add  the  second  fraction  and  distil  into  the  same 
receiver  till  the  thermometer  again  reaches  170°,  then  into  the 
second  receiver.  Establish  two  or  three  new  fractions,  accord- 
ing to  the  rate  at  which  the  thermometer  rises  as  the  acid  comes 
over,  the  object  being  to  obtain  as  large  a  fraction  as  possible 
within  an  interval  of  one  or  two  degrees  on  each  side  of  what 
appears  to  be  the  true  boiling-point  of  the  acid.  (See  p.  26  for 
further  details  and  for  corrections  for  the  thermometer.)  The 
fractional  distillation  should  be  repeated  till  a  main  fraction  is 
obtained  boiling,  in  this  case,  within  an  interval  of  one  degree. 
Yield  about  22  grams. 

Since  ordinary  amyl  alcohol,  or  fusel  oil,  consists  chiefly  of  3- 


3, 

methylbutanol,  >CHCH2CH2OH,     the     valeric      acid    ob- 

CH/ 

tained  from  it  will  consist  mainly  of  the  acid  corresponding  to 
this  formula.  Fusel  oil  contains,  however,  10  to  20  per  cent. 
of  what  is  supposed  to  be  a  partially  racemic  mixture  of  the  2- 


methyl  butanols,  >CHCH.2OH,  and  these  will,  of  course, 

CH/ 

give  the  corresponding  acids  by  oxidation.  Hence,  the  valeric 
acid  prepared  from  fusel  oil,  is  probably  a  mixture  of  at  least 
two  or  three  chemical  individuals.  The  perfectly  pure  isovaleric 
acid  (3-methyl  butanoic  acid)  can  be  obtained  by  conversion 
of  the  acid  into  the  barium  salt,  crystallizing  the  latter  from 
water  and  then  separating-  the  acid  from  the  pure  salt. 

Pure  isovaleric  acid  is  a  colorless  liquid  with  an  unpleasant 
odor.  It  boils  at  176.3°  and  has  a  specific  gravity  of  0.931  at 
20°.  It  dissolves  in  23.6  parts  of  water  at  20°,  but  the  addition 
of  soluble  salts  causes  most  of  it.  to  separate  from  the  solution. 
The  chromic  acid  mixture  oxidizes  it  to  acetic*  acid  and  carbon 
dioxide. 


ACIDS  I 19 

The  barium  salt  crystallizes  in  small  primus  or  thin  leaflets. 
The  silver  salt  crystallizes  in  leaflets  soluble  in  400  parts  of  water 
at  20°,  or  in  204  parts  of  water  at  80°.  The  salts,  when  thrown 
on  water,  rotate  rapidly.  This  is  characteristic  of  the  salts  of 
many  of  the  higher  fatty  acids. 

The  most  serious  objection  to  this  preparation  is  the  very  un- 
pleasant odor  accompanying  it.  The  operations  should  be  con- 
ducted under  a  hood  as  far  as  possible,  and  care  should  be  taken 
to  avoid  contact  of  the  valeric  acid  with  the  hands  or  clothing. 

47.  Oxidation  of  a  Ketone. — Separation  of  Two  Fatty  Acids. 
-Propionic  and  butyric  acids.  C,H,CO,H  and  C,H-CO2H  (pro- 
panoic  and  butanoic  acids). 

Literature — Papow :  Ann.,  145,  283;  161,  291;  Liebig:  Ibid,  7*,  355: 
Fitz:  Ber.,  n,  46;  Hecht :  Ann.,  209,  319;  Erlenmeyer  u.  Hill:  Ibid,  160, 
296;  Baeyer:  Ibid,  278,  101. 

10  grams  normal  butyric  acid   (butanoic  acid). 

25   grams  quicklime. 

6  grams  dipropylketone   (4  heptanone). 

25  grams  potassium  pyrochromate. 

1 20  cc.   water. 

20  cc.  concentrated  sulphuric  acid. 

Weigh  in  a  small  porcelain  dish  10  grams  of  normal  butyric 
acid.  Add  carefully,  taking  care  that  the  mixture  does  not  be- 
come so  hot  as  to  volatilize  any  appreciable  amount  of  the  acid, 
25  grams  of  powdered  quicklime.  Mix  thoroughly  and  powder 
in  a  mortar.  Place  the  mixture  in  a  50  cc.  flask,  clamp  the  lat- 
ter in  a  horizontal  position,  and  connect  it  by  means  of  perforated 
cork  stoppers  and  a  bent  glass  tube  with  a  small  condenser. 
Distil  by  heating  carefully  with  a  free  flame.  Collect  the  dis- 
tillate in  a  small  flask,  add  a  little  dry  potassium  carbonate  to 
remove  a  small  amount  of  acid  and  water  which  are  present, 
weigh,  pour  off  into  a  500  cc.  flask  and  weigh  again  to  deter- 
mine the  amount  of  crude  ketone  formed.  For  six  grams  of  the 
ketone  add  a  cooled  mixture  of  25  grams  potassium  pyrochro- 
mate, 20  cc.  concentrated  sulphuric  acid  and  120  cc.  of  water, 
using  more  or  less,  according  to  the  amount  of  thr  ketone.  Boil 


I2O 


ORGANIC    CHEMISTRY 


for  three  hours  on  a  thin  asbestos  plate,  with  a  reversed  con- 
denser (Fig.  24,  p.  68).  Transfer  the  mixture  to  a  200  cc.  dis- 
tilling bulb  and  distil  in  a  current  of  steam  (Fig.  25,  p.  54),  col- 
lecting the  distillate  in  successive  portions  of  10,  25,  50,  and  100 
cc.  Prepare,  separately,  calcium  salts  of  the  acid  in  the  first  and 
last  portions  by  boiling  for  a  short  time  with  a  small  quantity 
of  pure  calcium  carbonate,  and  filtering.  Concentrate  each  solu- 
tion to  10  cc.  or  less,  and  add  5  cc.  of  a  ten  per  cent,  solution  of 
silver  nitrate.  Filter  off  the  silver  salt,  best  on  a  small  Witt 
plate  (Fig.  29),  wash,  dry,  and  determine  the  per  cent,  of  silver 


Fig.  29. 

in  each  salt  by  careful  ignition  in  a.  porcelain  crucible. 

The  oxidation  gives,  in  this  case,  a  mixture  of  propionic  and 
butyric  acids.  On  distilling  the  mixture  in  a  current  of  steam 
the  butyric  acid,  which  is  less  soluble  and  which  also  has  the 
lower  ionization  constant,1  comes  over  mainly  in  the  first  portion, 
while  the  propionic  acid  comes  over  afterwards.  A  single  distil- 
lation as  directed  will  usually,  when  but  two  acids  are  present, 
give  a  sufficient  separation  so  that  the  analyses  of  the  silver  salts 
leave  no  question  as  to  the  composition  of  the  acids. 

Butyric  acid  boils  at  162°,  and  has  a  specific  gravity  of  0.978 
at  o°.  Propionic  acid  boils  at  141°,  and  has  a  specific  gravity 
of  1.013  at  o°. 

1  The  ionization  constants  should  be  found  in  Beilstein's  Handbuch. 


ACIDS  121 

100  parts  of  water  dissolve  0.48  parts  of  normal  silver  butyrate 
and  0.836. parts  of  silver  propionate  at  20°. 

48.  Preparation  of  an  Acid  from  a  Natural  Product, — Stearic 
acid,  C17H33CO2H. 

Literature — Pebal :  Ann.,  91,  138 ;  Heintz  :  Ann.,  92>  290 ;  C'arnelly,  Wil- 
liams :  Ber.,  12,  1360;  J.  Chem.  Soc.,  35,  563;  Krafft:  Ber.,  15,  1724;  16, 
1722;  Saunders:  Jahresb.,  1880,  831;  David:  Z.  anal.  Chem.,  18,  622; 
Krafft:  Ber.,  22,  819;  Hehner  and  Mitchell:  J.  Am.  Chem.  Soc.,  iQ>  32. 

100  cc.  alcohol. 
100  grams  tallow. 

35  grams  potassium  hydroxide. 
35  cc.  water. 

90  cc.  hydrochloric  acid  (sp.  gr.  i.i). 
Magnesium  acetate. 

Melt  zoo  grams  of  tallow  and  pour  it  into  a  500  cc.  flask,  add 
100  cc.  of  alcohol  and  warm  on  a  water-bath.  Add  in  small  por- 
tions 35  grams  of  caustic  potash  dissolved  in  35  cc.  of  water. 
After  all  has  been  added,  dilute  with  200  cc.  of  cold  water.  Add 
90  cc.  of  hydrochloric  acid  (4  cc.  =  I  gram),  and  warm  till  the 
fatty  acids  melt  and  collect  on  top.  Cool  and  separate  the  acids 
from  the  solution.  Dissolve  'the  acids  in  500  cc.  of  warm  al- 
cohol, cool  somewhat,  and  add  enough  of  a  solution  of  magnesium 
acetate1  to  precipitate  20  grams  of  stearic  acid.  Stir  for  five 
minutes,  filter  on  a  plate,  and  wash  once  with  strong  alcohol. 
To  the  filtrate  add  the  same  amount  of  the  acetate,  filter  on 
a  new  filter,  and  repeat  as  often  as  a  precipitate  is  obtained. 
From  the  last  filtrate  an  impure  oleic  acid  can  be  precipitated  by 
water. 

Decompose  each  of  the  magnesium  precipitates  separately  by 
warming  and  stirring  with  dilute  hydrochloric  acid  till  the  fatty 
acid  separates  and  melts  to  a  clear  liquid,  and  then  allow  each  to 
cool  and  solidify.  Crystallize  each  portion  of  the  acids  obtained 
from  15-20  times  its  weight  of  strong  alcohol.  Determine  the 

1  Prepare  the  solution  by  dissolving  16.8  grams  of  magnesium  carbonate  or  8  grams  of 
freshly  ignited  magnesium  oxide  in  85  cc.  of  acetic  acid  (30  per  cent.),  filtering,  and 
washing  to  a  volume  of  100  cc.  One  cc.  of  the  solution  will  precipitate  1.136  grams  stearic 
acid. 


122  ORGANIC    CHEMISTRY 

melting-points  of  each  set  of  crystals  obtained,  unite  portions 
having  nearly  the  same  melting-point  and-  crystallize  .again,  and 
repeat  till  a  considerable  quantity  of  pure  stearic  acid  is  ob- 
tained. It  will  usually  be  found  best  to  crystallize  rather  slowly 
by  spontaneous  cooling,  and  not  to  allow  the  temperature  to  fall 
too  low.  It  is  also  wise  to  separate  the  crystals  from  the  mother 
liquors  soon  after  they  form,  as  the  mother  liquors,  in  fractional 
crystallization  will  often  form  supersaturated  solutions  of  the 
substance  which  is  to  be  removed. 

The  impure  oleic  acid  referred  to  above  may,  if  desired,  be 
converted  into  the  lead  salt  by  digesting  with  litharge  on  the 
water-bath,  and  the  lead  oleate  separated  from  the  lead  salts  of 
other  acids  by  solution  in  ether,  or  in  alcohol  (of  sp.  gr.  0.82) 
at  65°.  The  oleic  acid  is  set  free  by  digesting  the  salt  with  hy- 
drochloric acid,  the  acid  converted  into  the  barium  salt,  and 
the  latter  crystallized  from  alcohol.  (Gottlieb:  Ann.,  57,  38.) 

Distillation  under  diminished  pressure  may  also  be  used  with 
advantage  in  purifying  the  fatty  acids.  The  boiling-points  and 
melting-points  are  as  follows: 

BOIUNG-POINTS 

Palmitic  Stearic  Oleic 

At    15  mm  ............          215°  232°  232.5° 

At  100  mm  .........  ...          271.8°  291°  286° 

At  760  mm  ............     339°-356°  359°-383° 

MEETING-POINTS 

Palmitic  Stearic  Oleic 

62°  69.2°  or  7i°-7i.5°  14° 

Stearic  acid  crystallizes  from  alcohol  in  leaflets.  It  is  solu- 
ble in  40  parts  of  cold  absolute  alcohol,  in  its  own  weight  of 
alcohol  at  50°. 

Palmitic  acid  dissolves  in  10  parts  of  cold  alcohol.  100  cc. 
of  alcohol  of  sp.  gr.  0.8183  will  dissolve  at  o°  about  0.15  gram 
of  stearic  acid  and  about  1.2  gram  of  palmitic  acid.  (Hehner 
and  Mitchell.) 

49.  Oxidation  of  a  Cyclic  Ketone.  —  Camphoric  acid, 


XCO,H 


ACIDS  123 

Literature — Kosegarten :  Dissertation,  Gottingen,  1785;  Laurent:  Ann., 
22»  135;  Wreden:  Ibid,  163,  323;  Maissen :  Ber.,  13,  1873;  Helle :  Dis- 
sertation, Bonn,  1893 ;  Noyes :  Am.  Chem.  J.,  16,  501 ;  Aschan :  Structur 
und  Stereochemische  Studien  in  der  Campher  Gruppe,  Helsingfors,  1895, 
Structure  of  Camphor,  Komppa :  Ann.,  37°,  209. 

/CH, 

50  grains  camphor,   C8HU^    j 

XCO 

300  cc.  nitric  acid  (sp.  gr.   1.42). 
200  cc.   water. 

Place  in  a  one  liter  flask  50  grams  of  camphor,  200  cc.  of 
water  and  300  cc.  of  nitric  acid  (sp.  gr.  1.42).  Close  the 
mouth  of  the  flask  with  a  tube  of  the  form  shown  in  the  cut, 
filled  with  water.  The  tube  is  easily  made  by  taking  a  tube 


40  cm.  long,  which  will  pass  easily  into  the  neck  of  the  flask, 
sealing  it  at  one  end,  and  blowing  a  small  bulb  at  about  10  cm. 
from  the  sealed  end. 

Heat  the  mixture  on  a  boiling  water-bath  or  a  steam-bath  for 
seventy  two  hours.  Cool,  filter  off  the  camphoric  acid  with  the 
pump  on  a  Hirsch  funnel  or  a  Witt's  plate,  (Fig.  29,  p.  120)  using 
an  "S.  &  S."  hardened  filter.  After  sucking  away  the  mother- 
liquors,  stop  the  pump,  add  enough  water  to  barely  cover  the 
acid,  and  suck  off  again.  In  all  cases  where  the  substance  to  be 
washed  is  appreciably  soluble  this  method  should  be  employed, 
as  bodies  may,  in  this  way,  be  effectively  washed  by  the  use  of  a 


J24  ORGANIC    CHEMISTRY 

much  smaller  quantity  of  the  solvent  than  if  the  pump  is  allowed 
to  act  while  the  solvent  is  poured  over  the  precipitate.  By  wash- 
ing three  or  four  times  in  this  manner  the  nitric  acid  will  be 
almost  completely  removed,  and  the  camphoric  acid,  after  dry- 
ing, will  be  sufficiently  pure  for  many  purposes,  and  especially 
for  the  preparation  of  the  anhydride,  as  the  latter  is  easily  puri- 
fied by  crystallization  from  alcohol.  The  acid  will,  however, 
contain  some  unchanged  camphor  and,  probably,  a  small  amount 


, 

of  camphoramidic  acid,  C8HU<;  .     If  a  pure  acid  is  de- 

XC02H 

sired,  after  washing  once,  transfer  the  acid  to  a  beaker,  add  150 
cc.  of  water  and  60-65  cc.  of  ammonia  (0.96),  enough  to  convert 
the  acid  into  the  ammonium  salt.  Filter  the  cold  solution,  and 
add  it  slowly,  with  constant  stirring,  to  70  cc.  of  hydrochloric 
acid  (sp.  gr.  i.n,  4  cc.  =  I  gram  HC1).  Filter  on  a  plate  and 
wash  with  cold  water.  Yield  about  30  grams  of  pure  acid. 

The  acid  mother-liquors,  if  kept  separate  from  the  washings, 
may  be  brought  up  to  a  specific  gravity  of  1.29  by  the  addition 
of  strong  nitric  acid  and  used  for  a  second,  and  the  mother- 
liquors  of  that,  for  a  third  oxidation.  The  yield  in  the  later 
oxidations  will  be  somewhat  greater.  The  filtrate  from  the  third 
oxidation  will  contain  considerable  amounts  of  camphoronic  acid, 
C0Hn(C02H)3. 

Camphoric  acid  crystallizes  in  leaflets  or  prisms  which  melt  at 
187°.  In  a  ten  per  cent,  alcoholic  solution  it  shows  a  rotation 
of  polarized  light  [a]y  =  4-49  7°,  or  [a]^  =  4-47.8°.  100 
parts  of  water,  dissolve  0.625  parts  of  the  acid  at  12°,  and 
8  to  10  parts  at  100°.  On  heating  alone,  or  with  acetyl  chlo- 
ride, or  acetic  anhydride,  it  is  converted  into  the  anhydride, 


/C0\ 


The  latter  is  converted  by  ammonia  into  the 


ammonium  salts  of  a-camphoramidic  and  /?-camphoramidic  acids, 

yCONH2  /C0 

jX  »  which  on  heating  give  an  imide,  C8H14<^ 

XC0.2NH4  N 


ACIDS  125 

The  ammonium  salt  of  the  a-camphoramidic  acid  is  less  soluble 
than  that  of  the  /3-acid  while  sodium  salt  of  the  /?-camphoramidic 
acid  is  less  soluble  than  that  of  the  a-acid.  A  separation  of  the 
two  acids  can  be  easily  effected  on  the  basis  of  these  facts  and  of 
the  further  fact  that  both  acids  are  nearly  insoluble  in  water. 

50.  Oxidation  of  a  Homologue  of  Benzene  with  a  Halogen  Atom 
in  the  Side  Chain.— Benzoic  acid,  C6H5CO2H. 

Literature.— Grimaux,  Hauth :  Bull.  soc.  chim.,  7,  100;  Lunge:  Ber., 
10,  1275;  Carius:  Ann.,  148,  51  and  59;  Wagner:  Jahresb.,  1880,  1289; 
V.  Meyer :  Ber.,  24,  4251 ;  Sandmeyer :  Ibid,  i?»  2653. 

20  grams  benzyl  chloride. 

46  grams  nitric  acid  (sp.  gr.  1.42). 

55   grams   water. 

Put  into  a  300  cc.  flask  with  a  narrow  neck,  from  which  the 
lip  has  been  cut  off,  so  as  to  leave  the  neck  straight  to  the  top, 
20  grams  of  benzyl  chloride,  46  grams  (32  cc.)  of  concentrated 
nitric  acid,  and  55  cc.  of  water.  Slip  over  the  neck  of  the  flask 
a  short  piece  of  rubber  tubing,  and  pass  through  this  the  tube  of 
an  upright  condenser  of  such  size  as  to  just  pass  easily  into  the 
neck  of  the  flask.  By  this  means  a  tight  joint  is  formed,  and 
at  the  same  time  the  vapors  scarcely  come  in  contact  with  the 
rubber.  Place  the  flask  on  a  wire  gauze  and  boil  gently  for  2-3 
hours,  or  until  the  oxides  of  nitrogen  nearly  disappear  within 
the  flask,  and  the  benzoic  acid  formed  largely  sinks  to  the  bot- 
tom of  the  liquid.  There  is  some  tendency  for  the  liquid  to 
boil  explosively,  but  there  is  less  trouble  from  this  source  if  a 
round-bottomed  flask  is  used  and  this  is  heated  directly  over  a 
small  flame  which  is  brought  close  to  the  wire  gauze,  than  if  the 
flask  is  heated  on  a  sand  bath  or  on  an  asbestos  paper.  A 
boiling  capillary,  (Scudder:  J.  Am.  Chem.  Soc.,  25,  163)  or  a 
few  small  pieces  of  porous  porcelain  may  also  be  used  to  ad- 
vantage. 

Cool,  filter  on  a  plate,  suck  off  the  mother-liquors,  stop  the 
pump,  moisten  thoroughly  with  water  and  suck  off  again.  Dis- 
solve the  benzoic  acid  in  70  to  80  cc.  of  sodium  hydroxide  (10 
per  cent.),  added  to  alkaline  reaction,  filter  on  a  plain  moist 


126  ORGANIC    CHEMISTRY 

filter,  or  pour  off  from  any  benzyl  chloride  which  remains  un- 
dissolved,  put  the  solution  in  a  flask  or  large  beaker  and  pass 
through  it  a  rapid  current  of  steam  till  the  vapors  no  longer 
smell  of  benzyl  chloride.  Precipitate  the  benzoic  acid  again  by 
adding  18  to  20  cc.  of  concentrated  hydrochloric  acid.  Cool 
thoroughly,  filter  on  a  plate,  and  wash  once.  Crystallize  from 
a  mixture  of  30  cc.  of  alcohol  with  10  to  15  cc.  of  water. 

The  benzoic  acid  prepared  in  this  way  retains  a  little  chloro- 
benzoic  acid  from  which  it  appears  to  be  nearly  or  quite  im- 
possible to  free  it.  This  can  be  detected  by  heating  a  little 
of  the  acid,  mixed  with  sodium  carbonate,  on  platinum  foil  till 
it  chars,  adding  a  little  potassium  nitrate  and  heating  again  till 
white,  dissolving  the  residue  in  water  and  adding  dilute  nitric 
acid,  and  silver  nitrate.  Yield  13  to  15  grams. 

Benzoic  acid  cvrystallizes  in  needles  or  leaflets  which  melt  at 
121.4°.  It  boils  at  249°.  100  parts  water  dissolve  0.27  part  of 
the  acid  at  18°,  and  2.19  parts  at  75°.  An  impure  acid  is  more 
easily  soluble.  It  is  soluble  in  about  3  parts  of  strong  alcohol 
at  15°.  It  is  easily  volatile  with  water  vapor.  The  vapors  of 
the  acid  produce  a  coughing  sensation. 

51.  Oxidation  of  the  Side  Chain  of  a  Hydrocarbon  Derivative. 

/C02H 
—  Ortho-  and  para-nitrobenzoic  acids,  C6H  / 


Literature  —  Beilstein  :  Ann'.,  133.  41  ;  J37>  302  ;  Hofmann  :  Ibid,  97, 
207;  Weith:  Ber.,  7>  1057;  Monnet,  Reverdin,  Nolting:  Ibid,  12,  443; 
Nolting,  Witt:  Ibid,  18,  1336. 


40  grams  toluene. 

50  cc.  sulphuric  acid  (1.84). 

30  cc.  nitric  acid  (1.42). 


Place  in  a  300  cc.  flask,  40  grams  (46  cc.)  of  toluene  and  add 
in  small  portions  a  cooled  mixture  of  50  cc.  of  concentrated 
sulphuric  acid,  and  30  cc.  of  nitric  acid  (1.42).  Shake  vigor- 
ously and  cool  after  each  addition,  taking  care  that  the  tempera- 
ture does  not  rise  above  30°.  After  the  acid  has  all  been  added, 
shake  vigorously  for  ten  minutes,  keeping  the  temperature  down 


ACIDS 


127 


as  before.  Pour  into  about  700  cc.  of  water.  The  nitrotoluene 
will  now  sink  to  the  bottom.  Separate  from  the  acid  liquid  with 
a  separatory  funnel,  and  wash  by  shaking  the  nitrotoluene  again 
with  about  100  cc.  water.  In  this  and  all  similar  cases  where 
a  heavy  liquid  is  to  be  separated  from  water,  it  is  best  to  use  a 
flask  or  separatory  funnel  of  such  size  that  the  mixture  will 
fill  it  nearly  to  the  top,  as  otherwise  a  considerable  amount  of 
the  heavy  liquid  may  remain  floating  on  top  of  the  water. 
Separate  the  nitrotoluene  as  completely  as  possible  from  the  water, 
put  it  in  a  small  flask,  add  10  grams  of  fused,  granulated  cal- 
cium chloride,  and  warm  in  a  water-bath  with  the  flask  covered 


Fig-  31- 


with  a  watch-glass  for  half  an  hour,  or  allow  it  to  stand  over 
night.  Pour  the  nitrotoluene  off  into  a  distilling  bulb.  Distil,  us- 
ing a  glass  tube  as  a  condenser  (see  Fig.  n,  p.  26).  The  portion 
distilling  below  200°  consists  principally  of  unchanged  toluene, 
and  may  be  saved.  That  distilling  between  2OO°-24O°  consists 
chiefly  of  ortho-  and  paranitrotoluene,  while  that  boiling  above 
250°  consists  chiefly  of  dinitrotoluene.  Ortho-nitrotoluene  boils 
at  220°  and  melts  at  -  -  10.5°.  Paranitrotoluene  boils  at  239° 
and  melts  at  54°.  The  two  can  be  partially  separated  by  frac- 
tional distillation,  and  the  para  compound  can  be  obtained  pure 
by  crystallization  from  alcohol.  For  the  remainder  of  this  prep- 
aration the  mixture  boiling  from  2oo°-24O°  may  be  used. 


128 


ORGANIC    CHEMISTRY 


15  grams  mixed  nitrotoluenes. 

100  cc.  water. 

10  cc.  sodium  hydroxide  (10  per  cent.). 

35  grams  potassium  permanganate. 

350  cc.  water. 

Arrange  a  one  liter  flask  with  an  upright  condenser,  a  bent 
thistle  tube,  and  a  bent  tube  to  convey  steam  to  the  bottom 
of  the  flask,  as  indicated  in  the  figure.  (See  Fig.  32.) 

Place  in.  the  llask  15  grams  of  the  mixed  nitrotoluenes,  100 
cc.  of  water,  and  10  cc.  of  a  10  per  cent,  solution  of  sodium 
hydroxide.  Add  about  50  cc.  of  a  warm  10  per  cent,  solution 


Fig-  32. 

of  potassium  permanganate.  Pass  in  a  current  of  steam  rapid- 
ly till  the  solution  boils,  and  then  just  fast  enough  to  keep 
the  contents  of  the  flask  agitated,  and  so  that  a  small  amount 
of  steam  condenses  above.  Add  more  of  the  permanganate 
solution  at  frequent  intervals  till  35  grams  of  the  salt  in  all  have 
been  added.  Continue  the  current  of  steam  until  the  pink  color 
of  the  permanganate  disappears,  or  till  the  drops  of  nitrotoluene 
cease  to  appear  in  the  condenser.  If  unreduced  permanganate 
is  still  present,  add  a  few  drops  of  alcohol,  and  shake  to  reduce 
it.  Filter  hot,  from  the  oxides  of  manganese,  on  a  filter  plate 
or  Hirsch  funnel,  and  wash  twice  with  water.  Concentrate  the 
filtrate  to  about  40  cc.,  and  precipitate  the  mixed  ortho-  and 


ACIDS  129 

paranitrobenzoic  acids  with  25  cc.  of  concentrated  hydrochloric 
acid.  Cool  very  thoroughly,  filter  on  a  plate,  and  wash  twice 
with  a  very  small  amount  of  cold  water,  sucking  off  the  mother- 
liquors  thoroughly  each  time  (see  47,  p.  120).  Convert  into  the 
barium  salts  by  boiling  with  about  12  grams  of  barium  car- 
bonate and  200  cc.  of  water.  Filter  hot  and  cool  the  filtrate. 
A  considerable  portion  of  the  barium  salt  of  the  para  acid  will 
separate.  Filter,  wash  once  with  cold  water  and  concentrate  the 
filtrate  and  washings  to  a  very  small  volume.  Cool  quickly  and 
filter  at  once  on  a  plate.  Moisten  the  residue  several  times  with 
a  small  amount  of  cold  water  and  suck  off.  Concentrate  the 
filtrate  and  washings,  and  crystallize  the  ortho  salt  by  allowing 
the  cold,  concentrated  solution  to  stand  for  some  time.  Recrys- 
tallize  both  the  ortho  and  para  salts  from  hot  water,  saving  the 
mother-liquors  and  working  them  up  in  such  a  manner  as  to 
secure  as  large  an  amount  as  possible  of  each  salt  in  a  pure  con- 
dition. 

The  separation  of  two  substances  by  crystallization  is  a  prob- 
lem which  often  presents  itself  in  organic  chemistry,  and  it 
frequently  requires  very  careful  work  and  good  judgment  to 
secure  both  substances  in  pure  condition  without  serious  loss 
of  material.  As  the  substance  which  is  present  in  least  amount, 
or  which  is  most  easily  soluble,  is  liable  to  form  supersaturated 
solutions,  it  is  usually  advisable  to  filter  off  a  substance  which 
has  crystallized  as  scon  as  its  separation  from  the  solution  ap- 
pears to  be  practically  complete.  The  separation  can  frequently 
be  hastened  by  vigorous  stirring,  and  by  the  addition  of  a  frag- 
ment of  the  pure  substance,  when  crystals  are  slow  in  starting. 
Occasionally,  'however,  a  substance  may  form  crystals  suffi- 
ciently large  to  be  separated  mechanically  from  others  with 
which  they  are  mixed.  In  such  cases  the  crystallizations  must 
be  allowed  to  proceed  slowly  and  undisturbed,  and  it  may  be 
well  to  allow  the  solution  to  evaporate  slowly  at  ordinary  tem- 
peratures, o-r  in  vacua  over  sulphuric  acid.  Large  crystals  of 
the  barium  salt  of  orthonitrobenzoic  acid  may  be  obtained  in  this 
way. 

9 


J3O  ORGANIC    CHEMISTRY 

Crusts  which  separate  on  the  walls  of  a  dish  or  beaker  dur- 
ing evaporation,  usually  consist  of  a  mixture,  and  should  be 
brought  back  into  the  solution  and  redissolved  by  heating  before 
the  latter  is  cooled  for  crystallization.  The  formation  of  such 
crusts  can  best  be  avoided  by  allowing  solutions  in  volatile  sol- 
vents, as  benzene  or  alcohol,  to  stand  during  crystallization  in 
tightly  closed  flasks.  Wide  mouthed  Erlenmeyer  or  Soxhlet 
flasks  are  very  useful  for  this  purpose. 

In  using  a  solvent,  a  very  common  mistake  is  to  use  too  large 
an  amount.  A  small  amount  should  always  be  added  at  first, 
unless  the  properties  of  the  substance  are  familiar,  and  then 
more,  if  the  substance  cannot  be  brought  into  solution. 

With  substances  which  separate  very  easily  on  cooling  the  so- 
lution/the  opposite  mistake  may  be  made,  if  the  solution  requires 
filtration.  In  such  cases,  the  substance  should  be  taken  only  in 
such  amount  as  will  dissolve  very  easily  in  the  amount  of  the 
solvent  used,  and  care  must  be  taken  to  prevent  the  crystalliza- 
tion of  the  substance  on  the  filter,  either  by  the  use  of  a  plate, 
(not  a  Hirsch  funnel),  and  pouring  only  as  fast  as  the  solution 
runs  through  the  filter,  or  by  the  use  of  a  hot  water  funnel. 
The  latter  is  rarely  necessary,  if  the  chemist  has  acquired  the 
necessary  experience,  except  in  cases  where  a  precipitate  clogs 
the  filter  badly. 

When  alcohol  is  used  as  a  solvent,  the  yield  of  crystals  may, 
sometimes,  be  increased  by  adding  some  water  to  the  solution 
before  it  cools.  When  the  impurities  are  soluble  in  dilute  alco- 
hol, this  may  be  used  with  advantage  instead  of  pure  alcohol 
to  wash  the  crystals. 

It  should  be  remembered  that  strong  alcohol  is  not  a  suitable 
solvent  for  some  acids  and  some  nitro-phenols  because  of  the 
.ease  with  which  they  form  esters. 

Crystallization  is  the  most  valuable  means  in  the  hands  of  the 
chemist  for  obtaining  pure  substances.  When  it  can  be  applied, 
it  almost  always  gives  purer  substances  than  fractional  dis- 
tillation. In  working  with  new  substances,  success  often  depends 
largely  on  the  choice  and  use  of  proper  solvents,  and  it  is  a  mat- 
ter to  which  the  beginner  should  give  very  careful  attention. 


ACIDS  •  131 

In  working  with  new  compounds  valuable  hints  can  almost  al- 
ways be  obtained  by  learning  from  text-books  or  chemical  jour- 
nals the  conduct  of  closely  related  substances  which  have  been 
previously  known. 

Orthonitrobenzoic  acid  crystallizes  in  colorless  triclinic  prisms, 
which  have  a  sweet  taste,  melt  at  147°,  and  dissolve  in  164  parts 
of  water  at  16.5°. 

Paranitrobenzoic  acid  crystallizes  in  yellow  leaflets,  which  melt 
at  240°,  and  dissolve  in  1200  parts  of  water  at  17°,  or  in  140 
parts  at  100°. 

The  barium  salt  of  the  ortho  acid  crystallizes  with  3  molecules 
of  water,  in  yellow,  triclinic  crystals,  which  are  easily  soluble 
in  water. 

The  barium  salt  of  the  para  acid  crystallizes  with  5  molecules 
of  water,  in  yellow,  monoclinic  prisms,  soluble  in  250  parts  of 
cold,  and  8  parts  of  hot  water. 

52.  Preparation  of  an  Acid  from  an  Amine  through  a  Diazo- 

/CH,      (i) 
nium  Compound. — Paratoluic  acid,  C6H4<( 

XC02H   (4) 

Literature — Spica  and  Paterno:  Ber.,  8,  441;  Sandmeyer :  Ibid,  17, 
1633,  2653;  18,  1492;  Baeyer  and  Tutein :  Ibid,  22,  2178;  Herb:  Ann., 
258,  8. 

21.4  grams  paratoluidine. 

39  grams  concentrated  hydrochloric  acid. 

150  cc.  water. 

50  grams  ice. 

14  grams  sodium  nitrate. 
70  cc.  water. 

55    grams    potassium   cyanide. 
100  cc.  water. 

50  grams  copper  sulphate, 
loo  cc.  water. 

10  grams  tolunitrile. 

30  cc.  concentrated  sulphuric  acid. 

20  cc.  water. 


132  ORGANIC    CHEMISTRY 

In  a  one  liter  flask  dissolve  50  grams  of  copper  sulphate  in 
100  cc.  of  hot  water.  When  the  diazonium  solution,  given  be- 
low, has  been  prepared,  pour  into  the  solution  of  copper  sulphate, 
slowly,  while  the  latter  is  heated  to  gentle  boiling,  in  a  hood  with 
a  good  draught,  55  grams  of  potassium  cyanide  dissolved  in  100 
cc.  of  water.  This  converts  the  copper  into  cuprous  cyanide 
with  evolution  of  cyanogen.  If  the  cuprous  cyanide  solution 
turns  dark  very  rapidly,  azulmic  acid  is  formed  by  the  decom- 
position of  cyanogen  held  in  solution.  The  presence  of  any  ap- 
preciable quantity  of  this  azulmic  acid  acts  very  unfavorably 
on  the  formation  of  the  nitrile  later.  By  boiling  the  copper  sul- 
phate solution  gently  during  the  addition  of  the  potassium  cy- 
anide solution  and  by  continuing  the  boiling  for  a  few  minutes 
at  the  end  to  expel  the  cyanogen  a  perfectly  clear,  slightly  col- 
ored solution  of  cuprous  cyanide  will  be  obtained. 

Put  into  a  400  cc.  beaker  21  grams  of  paratoluidine,  add  150 
cc.  of  water,  and  39  grams  (33  cc.)  of  concentrated  hydrochloric 
acid  (sp.  gr.  1.19).  Add  50  grams  of  ice,  and  when  the  tem- 
perature has  fallen  nearly  to  o°,  add,  in  small  portions,  with 
stirring  a  solution  of  14  grams  of  sodium  nitrite  in  70  cc.  of 
water.  For  a  discussion  of  the  best  condition  for  Sandmeyer's 
reaction  see  92,  p.  202. 

After  five  or  ten  minutes,  having  meanwhile,  completed  the 
preparation  of  the  cuprous  cyanide  solution,  place  in  the  mouth 
of  the  flask  containing  it  a  funnel,  and  pour  in  the  diazonium  so- 
lution, shaking  the  flask  and  keeping  it  hot  on  a  boiling  water- 
bath,  taking  care  also  that  the  solution  does  not  froth  over.  As 
soon  as  all  of  the  solution  has  been  added,  distil  off  the  nitrile 
in  a  rapid  current  of  steam  (see  Fig.  25,  p.  71).  If  the  dis- 
tillation is  sufficiently  rapid,  the  nitrile  will  come  over  with 
300  to  400  cc.  of  water.  Cool  the  distillate  in  ice-water  or  a 
freezing  mixture,  till  the  nitrile  solidifies,  and  separate  the  latter 
by  quick  filtration  on  a  plate,  or  an  a  funnel  loosely  stoppered 
with  cotton-wool.  Care  must  be  taken  to  transfer  the  nitrile 
to  a  dish  or  a  bottle  before  it  melts.  If  thought  better,  the  nitrile 
can  be  brought  to  the  surface  by  adding  salt  to  the  water,  or  it 


ACIDS  133 

may  be  collected  with  a  little  ether,  and  separated  with  a  sep- 
aratory  funnel.     Yield  about  15  grams. 

Tolunitrile  melts  at  28.5°' and  boils  at  218°. 

For  10  grams  of  tolunitrile  take  a  mixture  of  30  cc.  of  con- 
centrated sulphuric  acid  with  20  cc.  of  water.  Boil  in  a  small 
round-bottomed  flask  on  an  asbestos  plate  with  an  upright  con- 
denser till  crystals  of  toluic  acid  appear  in  the  latter.  Cool, 
dilute,  filter.  Put  the  acid  in  a  flask,  dissolve  in  a  little  alcohol, 
and  add  hot  water  till  the  solution  becomes  turbid.  Add  2  or  3 
grams  of  animal  charcoal,  boil  a  short  time,  filter  hot,  and  allow 
the  acid  to  crystallize.  Yield  8  to  9  grams  from  10  grams  of 
the  nitrile. 

Toluic  acid  crystallizes  in  white  needles,  which  melt  at  177°. 
It  is  very  easily  soluble  in  alcohol  and  ether,  and  easily  soluble 
in  hot  water.  It  volatilizes  readily  with  water  vapor.  In  alka- 
line solution  it  is  easily  oxidized  to  terephthalic  acid  by  po- 
tassium permanganate. 

53.  Condensation  of  an  Aldehyde  with  the  Sodium  Salt  of  an 
Acid.  Perkin's  Synthesis. — Cinnamic  acid, 

C6H5  —  CH  =  CHCO2H. 

Literature — Perkin :  Jsb.  d.  chem.,  1877,  789;  J.  Chem.  Soc.,  31,  388; 
Tiemann,  Herzf  eld :  Ber.,  10,  68;  Edeleano,  Budistheano :  Bull.  soc.  chim. 
[3],  3,  191;  Michael:  Am.  Chem.  J.,  5>  205.  Also  see  preparation,  39- 

20  grams  benzaldehyde. 
30  grams  acetic  anhydride. 
10  grams  sodium  acetate. 

In  a  100  cc.  flask  place  10  grams  of  recently  fused  and 
powdered,  dry,  sodium  acetate,  30  grams  acetic  anhydride,  and 
30  grams  benzaldehyde,  both  recently  distilled.  Connect  with  an 
upright  air  condenser  tube,  I  cm.  in  diameter  and  60-80  cm.  long. 
Heat  in  a  small  paraffin  bath  to  the  boiling-point  of  the  mixture, 
about  180°,  for  eight  hours.  Pour  the  contents  of  the  flask 
while  hot  into  a  500  cc.  flask  or  distilling  bulb.  Rinse  out  with 
hot  water  and  then  distil  with  water  vapor  as  long  as  benzalde- 
hyde comes  over.  Add  more  water,  if  necessary,  to  dissolve 
the  cinnamic  acid,  and  a  little  bone-black.  Boil  and  filter  hot 


134  ORGANIC    CHEMISTRY 

on  a  plain  or  plaited  filter,  previously  moistened.  To  the  filtrate 
add  13  cc.  of  concentrated  hydrochloric  acid.  (Why  is  this  de- 
sirable according  to  the  theory  of  ionization?)  The  cinnamic 
acid  will  crystallize  from  the  filtrate  on  cooling.  If  it  does  not 
have  the  proper  melting-point,  recrystallize  from  hot  water. 

Cinnamic  acid  crystallizes  from  water  in  colorless  needles  or 
leaflets,  which  melt  at  133°.  It  dissolves  in  3500  parts  of  water 
at  17°,  much  more  easily  in  hot  water.  It  combines  with  bromine 
to  form  a  dibromide,  C6H5CHBr.CHBrCO2H,  which  on  treatment 
with  alcoholic  potash  gives  phenyl  propiolic  acid,  C6H5C  —  C  - 
CO2H.  Ordinary  cinnamic  acid  appears  to  be  the  cistrans  modi- 

C6H5  -  CH 

fication,  .    Three  other  forms,  one  called  iso- 

H  —  C  —  CO2H 

cinnamic  acid,  which  melts  at  58°,  one  called  allocinnamic  acid, 
which  melts  at  68°,  and  a  fourth  isocinnamic  acid,  which  melts 
at  42°,  are  known.  Since  the  accepted  theory  of  stereoisomer- 
ism  will  account  for  only  two  isomers  or  stereomers,  the  exist- 
ence of  these  forms  has  led  to  a  very  careful  investigation  of 
these  acids.  Liebermann:  Ber.,  23,  141,  2511;  24,  1102;  25,  950; 
26,  1572;  27,  2038;  Fock:  Ibid,  23,  147,  2511;  Ostwald: 
Ibid,  23,  516;  24,  1106;  Stohmann:  Z.  physik.  Chem.,  10,  418; 
Michael:  Ber.,  34,  3640;  Erlenmeyer,  Jun. :  Ber.,  38,  3499;  39, 
285;  Erlenmeyer  and  Barkow:  Ber.,  39,  1570;  Biilmann :  Ber., 
42,  182 ;  43,  568 ;  Riiber  and  Goldschmidt :  Ber.,  43,  453 ;  Lieber- 
mann, Ber.,  42,  1027. 

A  final  conclusion  has  not,  perhaps,  been  reached  but  the  pres- 
ent tendency  is  to  explain  the  extra  forms  on  the  basis  of  poly- 
morphism. 

For  a  quite  different  method  of  preparing  cinnamic  acid 
see  39.  P-  99- 

54.  Reduction  of  an  Unsaturated  Acid  by  Sodium  Amalgam. 
— Hydrocinnamic  acid,  C6H5CH2CH2CO2H,  ( Phen-3-propanoic 
acid). 

Literature — Alexejew,  Erlenmeyer:  Ann.,  121,  375;  137,  327;  Gabriel, 
Zimmermann:  Ber.,  is»  1680;  Fittig,  Kiesow :  Ann.,  156,  249;  Sesemann: 
Ber.,  6,  1086;  10,  758;  Conrad,  Hodgkinson :  Ann.,  193,  300;  Conrad: 


ACIDS  135 

Ibid,  204,  174;  Conrad,  Bischoff:  Ibid,  204,  180;  Fittig,  Christ:  Ibid, 
268,  122.  For  benzyl  acetone,  Ehrlich :  Ibid,  187,  11;  Jackson : -Ber.,  14, 
890;  Harries,  Eschenbach :  Ibid,  29,  383. 

10  grams  cinnamic  acid. 

60  cc.  water. 

27  cc.   sodium   hydroxide    (10  per  cent.). 

135  grams  sodium  amalgam  (3  per  cent.). 

Put  in  a  200  cc.  wide-mouthed  bottle  10  grams  of  cinnamic 
acid,  60  cc.  of  water,  27  cc.  sodium  hydroxide  (10  per  cent.), 
and  135  grams  sodium  amalgam  (3  per  cent.).1  Shake  for 
some  time  till  the  amalgam  becomes  liquid.  Take  out  a  few 
drops  of  the  solution,  dilute,  pass  carbon  dioxide  through  it,  or 
add  a  few  drops  of  hydrochloric  acid,  a  little  sodium  car- 
bonate and  then  a  drop  of  a  very  dilute  solution  of  potassium 
permanganate.  If  the  permanganate  is  decolorized  or  turns 
brown  at  once,  cinnamic  acid  is  still  present  and  the  solution 
must  be  warmed  in  a  water-bath,  shaken  occasionally,  and,  if 
necessary,  more  amalgam  added  till  the  solution  no  longer  de- 
colorizes permanganate.  This  permanganate  test  has  proved  of 
great  value  for  the  detection  of  unsaturated  compounds  in  many 
similar  cases.  The  test  cannot  be  applied  to  the  alkaline  solu- 
tion without  passing  carbon  dioxide  through  it,  because  it  is 
masked  by  the  formation  of  a  green  manganate. 

When  the  reduction  is  complete,  pour  off  from  the  mercury 
and  precipitate  the  hydrocinnamic  acid  by  adding  22  to  25  cc. 
of  concentrated  hydrochloric  acid.  The  acid  usually  separates 
as  an  oil  which  solidifies  on  allowing  the  cold  solution  to  stand. 
Filter  off,  and  recrystallize  from  hot  water.  Yield  9  grams. 

Hydrocinnamic  acid  crystallizes  in  long  colorless  needles  which 
melt  at  49°.  It  boils  at  280°.  It  is  easily  soluble  in  boiling 
water,  in  alcohol,  and  in  ether.  It  is  volatile  with  water  vapor, 

1  Weigh  out  in  a  dry  mortar  130  grams  of  pure  mercury  (amalgam  from  impure  mer- 
cury is  much  less  effVctive;  Aschan:  Ber.  24,  1865;  E.  Fischer:  fbid.  25,  1255).  Cl«  an  4  grams 
of  sodium,  cutoff  a  thin  slice  and  press  it  to  the  bottom  of  the  mortar  with  the  pestle,  and 
press  gently  till  the  somewhat  violent  reaction  takes  place.  Add  a  second  piece  in  the 
same  way  and  continue  as  rapidly  as  possible  till  all  is  added.  If  the  operation  is  con- 
ducted quickly,  all  can  be  added  before  the  mass  solidifies.  Break  up  the  amalgam  at 
once  and  transfer  it  to  a  tightly  stoppered  bottle. 


136  ORGANIC    CHEMISTRY 

and  solutions  of  it  cannot  be  concentrated  by  boiling  without  loss. 
It  is  soluble  in  168  parts  of  water  at  20°. 

The  reduction  of  an  unsaturated  acid  by  sodium  amalgam  can 
only  be  carried  out,  apparently,  when  the  double  union  is  adja- 
cent to  the  carboxyl.  When  the  double  union  is  further  re- 
moved the  reduction  may  often  be  carried  out  by  first  adding 
Jiydriodic  acid  and  then  reducing  with  zinc  dust  or  the  zinc-cop- 
per couple  in  an  alcoholic  solution  and  in  presence  of  a  little 
dilute  acid.  See  6,  p.  42,  also  Noyes  and  Blanchard:  Am. 
Chem.  J.,  26,  288. 

The  reduction  may  also  be  effected  electrolytically  (Elbs: 
Uebungsbsp.  elektrolyt.  Darst.  chem.  Praparate;  see  also  Bredt: 
Ann.,  266,  13)  ;  by  ethyl  or  amyl  alcohol  and  sodium,  (Laden- 
burg,  Baeyer).  See  Einhorn:  Ann.,  286,  257;  295,  173;  Diels, 
Rhodius:  Ber.,  42,  1072;  by  hydrogen  in  the  presence  of  col- 
loidal platinum  or  palladium,  Paal  and  Gerum :  Ber.,  41,  2273. 
For  other  methods  of  reduction  see  Meyer:  Analyse  u.  Konsti- 
tutionsermittelung  org.  Verbindungen,  looking  up  "Reduktion" 
in  the  index. 

55.  Preparation  of  an  Ester  of  a  Bibasic  Acid  from  a  Halogen 
Derivative  of  an  Acid. — Malonic  ester,  CH 

Literature — Dessaignes:  Ann.,  107,  251;  Kolbe  and  Miiller:  Ibid,  131* 
348,  350;  Finckelstein :  Ibid,  i33>  338,  350;  Conrad:  Ibid,  204,  134;  Claisen 
and  Venable :  Ibid,  218,  131 ;  Kolbe  and  Miiller :  J.  Chem.  Soc.,  17,  109, 
(1864);  Noyes:  J.  Am.  "Chem.  Soc.,  18,  1105  (1896);  Presence  of  cy- 
anacetic  ester  in  malonic  ester,  Noyes :  J.  Am.  Chem.  Soc.,  23,  397 ; 
Preparation  of  cyanacetic  ester,  Ibid,  26,  1545. 

50  grams  monochloracetic  acid. 
45  grams  acid  sodium  carbonate. 
100  cc.  water. 

40  grams  potassium  cyanide. 

100  cc.  alcohol. 

80  cc.  concentrated  sulphuric  acid. 

Put  50  grams  of  monochloracetic  acid  into  a  porcelain  dish 


ACIDS  137 

20  cm.  in  diameter.  Add  100  cc.  of  water,  and  45  grams  of  acid 
sodium  carbonate.  Warm,  stirring  with  a  thermometer,  till  a 
temperature  of  50° -60°  is  reached,  and  the  effervescence  has 
ceased.  Place  the  dish  on  a  sheet  of  asbestos  paper  on  a  tripod, 
in  a  hood  with  a  good  draught.  Add  40  grams  of  powdered 
potassium  cyanide,  and  stir  vigorously  with  the  thermometer. 
Warm  only  very  gently  till  the  reaction,  which  takes  place  with 
considerable  evolution  of  heat  and  spontaneous  boiling  of  the 
solution,  is  complete.  Then  raise  the  flame  and  evaporate  rap- 
idly, stirring  constantly  with  the  thermometer  till  a  temperature 
of  130°  is  reached.  During  this  part  of  the  operation  keep  the 
window  glass  of  the  hood  between  the  dish  and  the  face,  and 
cover  the  hand  with  a  towel  or  glove  to  protect  it  from  the  par- 
ticles of  the  mixture  which  are  thrown  out.  '  Remove  the  dish 
from  the  flame,  and  continue  to  stir  till  the  mass  is  cold. 
Transfer  at  once  to  a  500  cc.  flask  as  the  mass  is  very  hygro- 
scopic. Connect  the  flask  with  an  upright  condenser  (see  20, 
p.  68).  Add  20  cc.  of  alcohol  and  then,  in  small  portions, 
through  the  condenser,  a  cooled  mixture  of  80  cc.  of  alcohol 
with  80  cc.  of  concentrated  sulphuric  acid.  After  each  addi- 
tion, mix  the  contents  of  the  flask  as  thoroughly  as  possible  by 
shaking.  When  all  of  the  mixture  has  been  added,  shake  till 
the  whole  is  thoroughly  mixed,  and  then  heat  on  the  water-bath 
for  an  hour.  Cool,  add  150  cc.  of  cold  water,  and  shake  thor- 
oughly. Filter  on  a  Hirsch  funnel  or  plate,  and  suck  the  liquid 
through  as  completely  as  possible.  Stop  the  pump,  moisten  the 
salt  with  ether;  after  a  minute  or  so  draw  this  through,  and 
repeat  twice.  Transfer  the  contents  of  the  filtering  flask  to  a 
separatory  funnel  and  draw  off  the  salt  solution  below.  Add  a 
small  amount  of  a  strong  solution  of  sodium  carbonate  to  the 
ethereal  solution,  and  shake  carefully  with  the  funnel  open 
at  the  top  to  allow  the  carbon  dioxide  to  escape.  When  enough 
of  the  solution  has  been  added  to  neutralize  the  free  acid, 
insert  the  stopper  and  shake  more  vigorously,  holding  the  stop- 
per firmly  in  place,  and  after  each  shaking  turning  the  funnel 
bottom-side  up  and  opening  the  stop-cock  to  relieve  the  pres- 
sure. Allow  the  two  layers  to  separate  as  completely  as  pos- 


138  ORGANIC    CHEMISTRY 

sible,  draw  off  the  aqueous  solution  below,  allowing  it  to  run 
into  the  first  acid  solution.  Transfer  the  ethereal  solution  of 
the  malonic  ester  to  a  distilling  bulb.  Distil  off  the  ether  on 
a  water-bath,  us;ng  a  condenser,  then  put  in  the  mouth  of  the 
bulb  a  rubber  stopper  bearing  a  tube  drawn  out  below  to  a 
fine  capillary,  which  reaches  nearly  to  the  bottom  of  the  bulb, 
and  attach  a  second  bulb  to  the  side  tube  (see  Fig.  34,  171, 
but  omit  the  thermometer).  Heat  in  the  water-bath  and  re- 
duce the  pressure  to  50  mm.,  or  less,  for  fifteen  minutes.  This 
method  of  drying  substances  which  boil  above  190°  is  usually 
quicker  and  more  satisfactory  than  the  use  of  calcium  chloride 
or  other  drying  agents.  Malonic  ester  may  also  be  dried  with 
advantage  by  allowing  it  to  stand  in  a  crystallizing  dish  in  a 
vacuum  desiccator  for  twenty-four  hours. 

After  drying,  distil  with  a  thermometer  and  condensing  tube 
(see  i,  p.  26).  Very  little  passes  over  below  190°,  and  that 
boiling  from  I9O°-2OO°  will  be  very  nearly  pure  malonic  ester, 
If  a  very  pure  ester  is  desired,  it  may  be  distilled  again,  and  only 
the  portion  boiling  within  one  degree  of  the  true  boiling-point 
taken.  Yield,  45  grams. 

The  sodium  carbonate  solution  contains  some  of  the  acid  ester. 
If  this  solution  is  added  to  the  first  acid  solution,  the  acid  ester 
separates  with  some  ether.  The  ethereal  solution  may  be  sep- 
arated, the  ether  evaporated  at  a  gentle  heat,  and  the  residue 
added  to  the  contents  of  the  flask,  in  which  a  second  saponifi- 
cation  of  the  cyanacetate  is  to  be  effected.  This  will  increase  the 
yield  to  50  grams. 

Malonic  ester  is  a  colorless  liquid  which  boils  at  198°,  and 
has  a  specific  gravity  of  1.061  at  15°.  It  is  decomposed  on  heat- 
ing to  150°  with  water,  giving  acetic  ester,  carbon  dioxide,  and 
alcohol.  (For  the  conduct  of  malonic  ester  toward  sodium 
ethylate  and  its  use  in  syntheses,  see  p.  in.) 

If  it  is  desired  to  prepare  malonic  acid,  after  adding  the 
potassium  cyanide  as  directed  above,  continue  to  heat  gently 
for  half  an  hour,  then  add  120  cc.  of  a  strong  solution  of  so- 
dium hydroxide  (3  cc.  =  i  gram'  NaOH),  and  continue  to  heat, 
replacing  the  water  which  evaporates,  as  long  as  the  evolution 


ACIDS  I3Q 

of  ammonia  continues,  usually  about  an  hour.  Add  carefully 
68  cc.  of  hydrochloric  acid  (4  cc.  =  I  gram  HC1),  and  a  solu- 
tion of  70  grams  of  calcium  chloride.  Filter,  wash  with  cold 
water,  and  dry  at  100°.  The  calcium  malonate  retains  two 
molecules  of  water.  To  obtain  the  free  acid  the  salt  is  decom- 
posed by  warming  with  the  calculated  amount  of  a  strong  so- 
lution of  oxalic  acid,  filtering  from  the  calcium  oxalate,  and 
evaporating  to  crystallization.  Malonic  acid  melts  at  134°  and 
dissolves  in  about  two-thirds  of  its  weight  of  water  at  16°.  At 
140°-! 50°  it  decomposes  into  carbon  dioxide  and  acetic  acid, 
a  reaction  characteristic  of  acids  having  two  carboxyls  combined 
with  one  carbon  atom. 

The  calcium  salt  is  almost  insoluble  in  cold  water. 

The  malonic  ester  prepared  by  the  directions  given  contains 

/CO.C.H, 

some  cyanacetic  ester,  CH9<f  ,   which-  does  not,    how- 

\CN 

ever  interfere  with  its  use  for  most  synthetical  purposes.  If 
pure  malonic  ester  is  required,  the  calcium  malonate  should  be 
prepared  as  directed  above.  This  salt  is  thoroughly  dried  and 
mixed  with  four  or  five  times  its  weight  of  absolute  alcohol 
and  dry  hydrochloric  acid  gas  passed  into  the  mixture  till  the 
salt  passes  into  solution.  After  boiling  for  two  or  three  hours 
with  a  reversed  condenser,  most  of  the  alcohol  is  distilled  off 
under  diminished  pressure  and  the  malonic  ester  separated  as 
above. 

56.  Preparation  of  a  Cyanide  and  Acid  from  a  Halogen  De- 

CH2  —  C02H 
rivative  of  a  Hydrocarbon.—  Succinic  acid, 

CH2  —  C02H 

Literature — Simpson:  Ann.,  118,  374;  121,  154;  Nevole  u.  Tscherniak: 
Bull.  soc.  chim.,  3°i  101 ;  Fauconnier:  Ibid,  5°,  214;  Brown,  Walker:  Chem. 
News,  66,  91:  Ann..  261,  115:  Liebig:  Ibid,  7°»  104,  363;  Konig:  Ber.,  i5t 
172. 


140  ORGANIC    CHEMISTRY 

50   grams    ethylene    bromide. 
100  cc.  alcohol. 

34  grams  potassium  cyanide. 

35  cc.  water.  - 

40  grams  potassium  hydroxide. 

65  cc.  concentrated  hydrochloric  acid. 

Place  in  a  300  cc.  flask  50  grams  of  ethylene  bromide  and  100 
cc.  of  alcohol.  Connect  with  an  upright  condenser,  heat  to  boil- 
ing on  a  water-bath,  and  drop  into  the  solution  slowly  from  a 
dropping  funnel  placed  in  the  top  of  the  condenser,  a  solution  of 
34  grams  of  potassium  cyanide  in  35  cc.  of  water.  After  the  solu- 
tion has  all  been  added,  boil  on  the  water-bath  for  an  hour  and 
a  half.  Cool,  and  pour  off  from  the  potassium  bromide  into 
a  flask  containing  40  grams  of  solid  potassium  hydroxide,  cool- 
ing, if  necessary,  to  prevent  too  violent  a  reaction  at  first.  Rinse 
the  residue  of  .potassium  bromide  twice  with  a  small  amount  of 
alcohol,  adding  the  rinsings  to  the  main  portion.  Boil  with  an 
upright  condenser  for  two  hours.  Pour  the  contents  of  the 
flask  into  a  porcelain  dish,  and  evaporate  on  the  water-bath  till 
the  alcohol  is  entirely  removed.  Add  fifty  cc.  of  water,  and  40 
cc.  of  concentrated  hydrochloric  acid,  and  filter.  To  the  filtrate 
add  25  cc.  more  of  concentrated  hydrochloric  acid,  cool  very 
thoroughly,  filter  off  the  succinic  acid,  and  crystallize  it  from 
hot  water.  The  yield  is  poor. 

Succinic  acid  crystallizes  from  water  in  tabular  crystals.  It 
melts  at  182°.  Tf  heated  above  its  melting-point,  it  is  converted 
into  the  anhydride.  100  parts  of  water  at  o°  dissolve  2.8,  at 
20°,  6.9  and  at  50°  24.4  parts  of  the  acid.  100  parts  of  alcohol 
at  12°  dissolve  7.5  parts,  and  100  parts  of  ether,  1.26  parts. 

Ethylene  cyanide  is  present  in  the  above  alcoholic  solution  and 
can  be  obtained  from  it  as  follows :  Pour  the  solution  off  from 
the  potassium  bromide  into  a  300  cc.  distilling  bulb,  rinse  as 
before  and  distil  off  as  much  of  the  alcohol  as  possible  on  the 
water-bath.  Transfer  to  a  100  cc.  bulb,  fitted  with  a  thermom- 
eter, capillary  tube,  and  receiving  bulb,  as  indicated  in  Fig.  34, 


ACIDS  141 

p.  171.  Distil  on  the  water-bath  under  diminished  pressure  as 
long  as  alcohol  or  Water  comes  over.  Then  change  the  receiver 
and  distil  carefully  over  a  free  flame,  or  in  an  oil-bath,  with  the 
pressure  as  low  as  possible. 

Ethylene  cyanide  boils,  under  10  mm.  pressure  at  147°,  under 
760  mm.  pressure  at  265° -267°,  with  partial  decomposition.  It 
melts  at  54°.  It  has  been  suggested  as  a  solvent  for  molecular 
weight  determinations  by  the  cryoscopic  method,  as  it  has  the 
highest  known  constant,  182.6.  It  cannot  be  used  for  substances 
which  ionize,  however,  as  its  ionizing  power  is  large.  Bruni, 
Mannelli:  Z.  Elektroch.,  n,  860. 

57.  Preparation  of  a  Condensation  Product  from  Phthalic  An- 
hydride.— Phenolphthalem, 

OH 
C6H  /   /O  -  CO 

C6H4/   \C6H4 

OH 

Literature — Baeyer :  Ann.,  202,  68;  183,  i;  Ber.,  9,  1230;  Knecht:  Ibid, 
15,  1068;  Ann.,  215,  83;  (Indicator)  Menschutkin :  Ber.,  16,  319;  H.  C. 
Jones  and  Allen:  Am.  Chem.  J.,  18,  377;  Structure  as  an  indicator, 
Orndorff:  Am.  Ch.  J.,  26,  no;  Stieglitz :  J.  Am.  Chem.  Soc.,  24,  590; 
A.  A.  Noyes,  Ibid,  32,  860. 

10  grams  phthalic  anhydride. 

8  grams  concentrated  sulphuric  acid. 

20  grams  phenol. 

Put  in  a  small  flask  10  grams  of  phthalic  anhydride,  8  grams 
of  concentrated  sulphuric  acid,  and  20  grams  of  crystallized 
phenol.  Heat  in  an  oil-bath,  with  a  thermometer  in  the  mixture, 
at  U5°-i2o°  for  ten  hours.  Pour  the  hot  mass  into  100  cc.  of 
boiling  water,  and  boil  till  the  odor  of  phenol  disappears,  filter 
hot,  and  wash.  Dissolve  the  residue  in  a  dilute  solution  of 
sodium  hydroxide,  filter,  precipitate  with  acetic  acid  and  a  few 
drops  of  hydrochloric  acid,  and  allow  to  stand  for  twelve  hours. 
Dry  the  residue,  dissolve  it  in  6  parts  of  boiling  alcohol,  add 
cne-half  its  weight  of  bone-black,  boil  for  some  time,  filter 


14-2  ORGANIC    CHEMISTRY 

and  wash  with  two  parts  of  hot  alcohol.  Distil  off  two-thirds 
of  the  alcohol,  and  add  a  very  little  water.  Filter,  or  pour  off, 
if  gummy  matters  separate,  and  precipitate  the  phenolphthalem 
with  water,  warming  for  a  few  minutes  to  cause  it  to  become 
crystalline. 

The  crystalline  phenol  phthalein  melts  at  250°  -253°.  Phenol- 
phthalem forms  salts  with  alkalies,  which  are  soluble  in  water 
with  a  deep  red  color.  These  solutions  probably  contain  salts 

^C.H,  =  O 
derived  from  the  quinoid  form,  C  —  C6H4OH      .         In  the  pres- 

\:6H4CO2H 
ence  of  hydrogen  ions  the  acid  which  is  formed  rearranges  at 


once  to  the  tautomeric  form,   C  —  C6H4OH,     which    is    colorless 

\C6H4CO 

I 

1  --  O 

and  which  has  only  the  very  faintly  acid  properties  characteristic 
of  phenols.  The  solutions  are  red  in  the  presence  of  alkalies, 
or  normal  carbonates,  but  colorless  in  the  presence  of  bicarbo- 
nates,  or  free  acids.  Owing  to  its  extreme  sensitiveness  to  even 
weak  acids,  phenol  phthalein  is  especially  suited  as  an  indicator 
for  the  titration  of  organic  acids. 

By  heating  with  concentrated  sulphuric  acid  at  200°,  phenol 
phthalein  is  converted  into  hydroxyanthraquinone, 

/C0\ 
C6H4<        >C6H3OH. 

XC(X 

If  resorcinol  is  used  in  place  of  phenol,  and  zinc  chloride  is 
used  as  a  condensing  agent,  (half  the  weight  of  the  phthalic 
a'nhydride),  the  temperature  being  raised  to  2OO°-2ii°  till  the 

O 


mass    becomes    solid,     fluorescein,  ,C  -  C6H  ,    s 

C«H'\COOH 


ACIDS  143 

formed.  By  treating  with  bromine  in  an  alcoholic  solution,  this 
is  converted  into  tetrabromfluorescem  (eosin).  Eosin  and  other 
similar  compounds,  and  also  anthracene  derivatives  which  are 
obtained  from  these  compounds  by  heating  with  concentrated 
sulphuric  acid  (see  above),  are  used  as  dyes. 

Compounds  of  the  fluorescein  type  are  only  formed  when  the 
hydroxyl  groups  of  the  phenol  are  in  the  meta  position  and  the 
third  meta  position  is  also  free. 


Chapter  VIII 

DERIVATIVES  OF  ACIDS 

The  derivatives-  of  organic  acids  are  of  two  classes:  those 
derivatives  in  which  the  carboxyl  (CO2H)  group  is  affected, 
and  those  in  which  the  rest  of  the  acid  is  changed.  To  the 
former  class  belong  salts,  chlorides,  anhydrides,  amides,  and 
esters ;  to  the  latter,  halogen  derivatives,  nitro  derivatives,  amino- 
acids,  hydroxy-acids,  and,  indeed,  nearly  or  quite  all  classes 
of  derivatives  which  may  be  formed  from  hydrocarbons.  Only 
the  first  class  of  derivatives  will  be  considered  in  this  chapter. 

The  chlorides  of  acids  are  prepared  by  treatment  of  the  acid, 
or  one  of  its  salts,  with  phosphorus  trichloride,  phosphorus 
pentachloride  or  phosphorus  oxychloride.  The  trichloride  is 
usually  used  for  the  lower  members  of  the  fatty  acid  series,  and 
for  cases  where  the  boiling-point  of  the  chloride  is  near  that  of 
phosphorus  oxychloride. 

O  O 

//  // 

3RC  -  -  OH  +  2PC13  =  3R  _  C  —  Cl  +  3HC1  +  P2O3. 

For  other  cases,  and  especially  when  acids  react  with  difficulty, 
phosphorus  pentachloride  is  used. 

O  O 

//  // 

R  —  C  —  OH  +  PC15  =  R  —  C  —  Cl  +  POC13  +  HC1. 

Phosphorus  oxychloride  is  rarely  used  except  with  the  salts 
of  acids. 

O  O 

//  // 

2R  —  C  —  ONa  +  POC13  =  2R  —  C  —  Cl  +  NaPO3  +  NaCl. 

The  anhydrides  of  monobasic  acids  are  usually  prepared  by 
the  action  of  the  chloride  of  the  acid  on  its  sodium  salt. 

O      O 

//  \ 

R  _  COC1  +  RCO.ONa  =  R  —  C  —  O  —  C  —  R  +  NaCl. 


DERIVATIVES  OF  ACIDS  145 

In  some  cases  an  excess  of  the  alkaline  salt  is  treated  with 
phosphorus  oxychloride. 

4R  __  CO.ONa  +  POC13  =  NaPO8  +  3NaCl  + 
2R_CO— O— CO— R. 

Bibasic  acids  in  which  the  two  carboxyl  groups  are  separated 
by  two  carbon  atoms,  either  in  the  aliphatic  or  aromatic  series 
(succinic  and  phthalic  acids  and  their  derivatives),  readily  form 
inner  anhydrides,  in  most  cases  by  the  action  of  heat  alone  and 
at  temperatures  below  210°.  (Auwers:  Ann.,  285,  223.)  The 
formation  of  such  anhydrides  can  be  effected  at  lower  tempera- 
tures, and  in  most  cases  quantitatively  by  the  use  of  acetyl 
chloride,  acetic  anhydride,  or  phosphorus  oxychloride. 

/CO,H  /OX 

2R<  +  POC13  =  2R<         >O  +  sHCl  +  HPO3. 

XC02H  NCCX 

Glutaric  acid  and  its  derivatives  with  open  chains  and,  ap- 
parently, the  "cis"  forms  of  cyclic  derivatives,  also  form  an- 
hydrides by  the  same  treatment,  but  isophthalic  acid  gives  no 
inner  anhydride. 

Amides  may  be  prepared  in  many  cases  by  heating  ammo- 
nium salts  of  acids. 

O  O 

//  // 

RC  —  ONH4  =  R  -  -  C  —  NH,  +  H2O. 

Another  method,  which  is  applicable  in  almost  all  cases  where 
the  resulting  amide  is  difficulty  soluble  in  water,  consists  in 
treating  the  acid  with  phosphorus  pentachloride  to  convert  it 
into  chloride,  and  then  adding  the  mixture  of  the  chloride  with 
phosphorus  oxychloride  carefully  to  cold  concentrated  aqueous 
ammonia,  or  ammonia  gas  may  be  passed  into  the  mixture,  diluted 
with  benzene,  ether,  or  chloroform.  In  some  cases  it  is  best  to  dis- 
til away  the  phosphorus  oxychloride  under  diminished  pressure 
before  adding  the  chloride  of  the  acid  to  the  ammonia.  In 
others  the  oxychloride  may  be  decomposed  by  ice-water  without 
decomposing  the  chloride  of  the  acid, 
ro 


146  ORGANIC    CHEMISTRY 

O  O 

//  // 

RC  —  Cl  +  2NH3  =  R  —  C  —  NH2  +  NH4C1. 
Esters,  on  treatment  with  ammonia,  are  converted  into  amides  : 
O  O 

//  // 

R  —  C  —  OR'  +  NH3  =  R  —  C  —  NH2  +  R'  —  OH. 

This  method  is  seldom  used,  except  in  cases  where  other 
methods  fail.  (See  Einhorn  and  Bull:  Ann.,  295,  207;  Noyes  : 
Am.  Chem.  J.,  20,  811.) 

The  preparation  of  amides  from  nitriles  or  cyanides  has  been 
referred  to  on  p.  108. 

Acids  which  form  inner  anhydrides  form  also  imides  in  which 
the  NH  group  takes  the  place  of  the  oxygen  atom  which  com- 
pletes the  ring  in  the  case  of  the  anhydride.  These  imides  may 
be  prepared  by  heating  the  ammonium  salt  of  the  acid: 

/CO  -  ONH4  /COV 

R<  =  R<         >NH  +  NH3  -f  H2O. 

XCO  —  ONH4  XCCK 

In  some  cases  the  ammonium  salt  of  the  half  amide  of  the 
acid  gives  better  results.  The  conversion  of  an  anhydride  into 
an  imide  by  the  action  of  ammonia,  or  ammonium  carbonate, 
probably  depends  on  the  intermediate  formation  of  such  a  salt: 

/C0\  /CO  —  NH2  /COV 

- 


>O  -f  2NH3  ==  R<  =  R<         >NH 

CK  XCO  —  ONH4          \CCK 

-f  NH3  rf-  H20. 

Closely  related  to  the  amides  are  anilides  and  similar  com- 
pounds, which  may  be  considered  either  as  amides  having  a 
hydrogen  atom  of  the  NH2  group  replaced  by  a  hydrocarbon 
residue,  or  as  an  amine  having  a  hydrogen  atom  of  the  amine 
group  replaced  by  an  acid  radical.  Anilides  and  similar  com- 
pounds may  frequently  be  prepared  by  simply  heating  the  acid 
with  the  amine,  water  being  eliminated  more  easily  than  in  the 
case  of  the  ammonium  salts. 

RCOOH  -f  R'NH2     =  R—  CO—  NHR'  +  H2O 

A  more  general  method  consists  in  treating  the  amine  with 


DERIVATIVES  OF  ACIDS  147 

the  chloride  or  anhydride  of  the  acid,  either  directly,  or  in  the 
presence  of  an  aqueous  solution  of  sodium  hydroxide.  ("Schot- 
ten-Baumann  reaction,"  see  65,  p.  154'.) 

Alkyl  or  aryl  cyanides  may  also  be  considered  as  derivatives 
of  acids  and  as  such  they  are  called  nit  riles.  From  this  point 
of  view  they  may  be  prepared  by  treating  the  amide  of  an  acid 
with  phosphorus  pentoxide : 

R— CONH2  +   P2O5     =     R— CN   +  2HPO3. 

The  preparation  of  cyanides  from  alkyl  halides  and  in  other 
ways  has  already  been  considered,  (p.  107). 

Esters  of  strong  acids  may  be  prepared  by  bringing  together 
the  acid  and  alcohol.  The  action  is  aided  by  heat.  The  reac- 
tion is,  however,  a  reversible  one  and  proceeds  only  till  an  equilib- 
rium is  established  between  the  amounts  of  ester,  water,  alco- 
hol, and  acid  present.  For  equivalent  weights  of  acid  and  alco- 
hol, the  per  cent,  of  ester  formed,  when  equilibrium  is  reached, 
is  characteristic  of  the  acid  and  alcohol  in  question,  and  varies 
greatly  in  different  cases.  Primary  alcohols  form  esters  more 
quickly  and  in  larger  amount  than  secondary,  and  secondary 
than  tertiary.  In  a  similar  manner  acids  with  a  primary  car- 
boxyl  (R — CH2CO,H)  form  esters  more  quickly  than  those 
with  secondary  carboxyl,  and  the  latter  more  quickly  than  those 
with  a  tertiary  carboxyl.  These  facts  may  be  used  to  determine 
the  structure  of  the  alcohols  and  acids  (Menschutkin,  see  third 
edition  of  Beilstein  I,  218  and  389.  For  a  practical  application 
in  determining  the  structure  of  an  acid  see  Noyes :  Am.  Chem.  J., 
18,  685). 

The  amount  of  an  acid  which  will  be  converted  into  an  ester 
is  increased  by  the  use  of  a  larger  amount  of  the  alcohol,  in 
accordance  with  the  law  of  mass  action,  which  applies  to  all  re- 
versible processes,  that  the  increase  of  the  amount  of  one  of  the 
reacting  substances  increases  the  amount  of  product  or  product? 
(in  this  case  ester  and  water)  which  result  from  its  action  on 
other  substances  present.  It  follows  that  an  excess  of  the  al- 
cohol should  be  used  when  the  acid  is  rare  or  expensive,  and  an 
excess  of  the  acid  when  the  alcohol  is  valuable. 


148  ORGANIC    CHEMISTRY 

In  most  cases  esterification  is  very  much  hastened  by  the  ad- 
dition of  hydrochloric  or  sulphuric  acid  to  a  mixture  of  an  or- 
ganic acid  and  alcohol.  It  was  formerly  supposed  to  be  nec- 
essary to  saturate  the  mixture  with  dry  hydrochloric  acid  gas, 
but  Emil  Fischer  has  shown  (Ber.,  28,  3252),  that  a  compara- 
tively small  amount  of  hydrochloric  or  sulphuric  acid  may  fre- 
quently be  used  with  better  advantage. 

Esters  may,  in  most  cases,  be  readily  prepared  from  the  chlo- 
rides of  acids  by  treatment  with  an  alcohol.  (See  Baeyer:  Ann., 
245,  140.) 

O  O 

//  // 

R— C— Cl  +  R'— O— H     =     RC— OR'  +  HC1. 

They  may  also  be  prepared  by  treating  a  silver  salt  of  an  acid 
with  an  alkyl  iodide, 

O  O 

//  // 

R— C— OAg  +  R'l     =     R— C— OR'  +  Agl. 

For  methyl  esters  dimethyl  sulphate  and  the  sodium  salt  of 
an  acid  may  be  used. 


58.  Preparation  of  an  Acid  Chloride. — Acetyl  chloride, 
CH3.COC1.  (Ethanoyl  chloride.) 

Literature — Bechamp:  Jsb.  d.  Chem.,  1855,  504;  1856,  427;  J.  prakt. 
Chem.,  65,  495 ;  Thorpe :  J.  Chem.  Soc.,  1880,  37>  186 ;  Bothamley,  Thomp- 
son :  Chem.  News.,  1890,  62,  191  ;  Gerhardt :  Ann.,  87,  63. 

100  grams  acetic  acid   (glacial). 

80  grams  phosphorus  trichloride. 

Arrange  a  300  cc.  distilling  bulb,  condenser  and  receiver  as 
indicated  in  Fig.  33. 

All  of  the  apparatus  must  be  absolutely  dry,  and  the  side 
tube  of  the  receiver  should  be  connected  with  a  tube  which  will 
deliver  the  hydrochloric  acid  evolved  immediately  over  the  sur- 
face of  some  water  in  a  bottle.  Place  in  the  distilling  bulb  100 
grams  (96  cc.)  of  glacial  acetic  acid,  and  add  through  the  drop- 
ping funnel  80  grams  of  phosphorus  trichloride.  Warm  for  a 
short  time,  gently,  till  the  evolution  of  hydrochloric  acid  nearly 


DERIVATIVES  OF  ACIDS 


149 


ceases  and  the  liquid  separates  in  two  layers.  Then  distil  from 
a  water-bath  as  long  as  anything  comes  over.  The  distillate 
usually  contains  some  phosphorus  trichloride.  If  a  product  en- 
tirely free  from  phosphorus  is  required,  add  two  or  three  grams 
of  powdered,  dry,  sodium  acetate,  allow  to  stand  over  night,  and 
distil  again  from  the  water-bath,  collecting  the  portion  boiling 
at  5o°-56°.  Yield  80  to  90  grams. 

Acetyl  chloride  is  a  colorless  liquid  with  a  very  disagreeable 
odor.     It  boils  at  50.9°,  and  has  a  specific  gravity  of  1.1051  at 


Fig.  33- 

20°.  It  decomposes  rapidly  with  water  or  moist  air  and  must 
be  kept  in  tightly  closed,  glass-stoppered,  or  sealed  bottles. 

Acetyl  chloride  reacts  readily  with  almost  all  bodies  containing 
either  an  alcoholic  hydroxyl,  or  an  amine  group.  In  both  cases 
a  hydrogen  atom  of  the  group  is  replaced  by  the  acetyl  group, 
Q2H3O.  The  resulting  compounds  are,  in  many  cases,  crys- 
talline and  difficultly  soluble  in  water,  and  hence  well  adapted 
for  the  characterization  of  substances  of  these  two  classes. 

59.  Preparation  of  an  Anhydride  of  an  Acid. — Acetic  anhy- 
O  O 

//  % 

dride,  CHSC  —  O  —  C  --  CH3.     (Ethanoic  anhydride.) 

Literature — Gerhardt:  Ann.,   (1852},  82,  131;  87,  149. 
60  grams  dry  sodium   acetate. 
50  grams  acetyl  chloride. 


15O  ORGANIC    CHEMISTRY 

Place  in  a  dry,  200  cc.  flask,  60  grams  of  freshly  fused,  dry, 
powdered  sodium  acetate,  and  connect  with  an  upright  condenser. 

Add,  in  small  portions,  through  the  condenser,  50  grams  of 
acetyl  chloride,  shaking  vigorously  after  each  addition.  Warm 
on  a  water-bath  as  long  as  any  acetyl  chloride  condenses  and  runs 
back.  Then  connect  the  flask  with  the  condenser  in  the  usual 
manner  by  means  of  rubber  stoppers  and  a  bent  tube,  and  distil 
slowly  with  a  free  flame,  holding  the  burner  in  the  hand.  Collect 
the  portions  boiling  at  I3O°-I42°.  Add  to  the  distillate  two 
or  three  grams  of  dry  sodium  acetate  and  distil  again.  Yield 
40  to  50  grams. 

Acetic  anhydride  is  a  colorless  liquid  with  an  unpleasant  odor. 
It  boils  at  138°,  and  has  a  specific  gravity  of  1.08  at  15°. 

When  most  compounds  containing  alcoholic  or  amine  groups 
acetic  anhydride  reacts,  giving  the  same  products  as  acetyl  chlo- 
ride. The  reaction  is  usually  less  violent,  and,  of  course,  no 
hydrochloric  acid  is  formed.  Since  acetic  anhydride  does  not 
react  very  quickly  with  cold  water,  it  may  be  used  for  the  Schot- 
ten-Baumann  reaction  (65  and  66,  pp.  154,  155),  while  acetyl 
chloride  cannot. 

60.  Preparation  of  the  Anhydride  of  a  Bibasic  Acid.  —  Succinic 


CH2  — 


anhydride, 


Literature  —  Gerhardt  u.  Chiozza:  Annv  87,  293;  Anschtitz  :  Ber.,  10, 
1883;  Ann.,  226,  8;  Volhard:  Ibid,  242,  150;  Auwers  :  Ibid,  285,  223. 

20  grams  succinic  acid. 

13  grams  phosphorus  oxychloride. 

Place  in  a  small  flask  20  grams  (2  mols.)  of  dry  succinic  acid. 
Add  13  grams  (i  mol.)  of  phosphorus  oxychloride.  Connect 
with  an  upright  condenser,  and  warm  gently  on  an  asbestos 
plate  so  long  as  hydrochloric  acid  escapes.  To  avoid  the  escape 
of  the  acid  into  the  room  connect  the  top  of  the  condenser  with 
a  tube  which  will  deliver  the  gas  just  above  the  surface  of  water 
in  a  bottle.  When  acid  ceases  to  escape,  transfer  to  a  50  cc. 


DERIVATIVES  OF  ACIDS  15 1 

distilling  bulb,  connect  with  an  air  condensing  tube,  and  distil. 
When  the  drops  coming  over  solidify  easily,  remove  the  condens- 
ing tube  and  distil  slowly  into  a  small  flask  without  any  con- 
denser. Crystallize  the  anhydride  from  chloroform.  Yield  al- 
most quantitative. 

Instead  of  phosphorus  oxychloride,  12  grams  of  phosphorus 
pentachloride  may  be  used  but,  in  that  case,  the  mixture  should 
be  warmed  on  the  water-bath  till  it  becomes  liquid  before  plac- 
ing it  on  the  asbestos  plate  over  the  free  flame. 

Succinic  anhydride  crystallizes  from  chloroform  or  acetic 
anhydride  in  needles,  which  melt  at  119.6°.  It  boils  at  261°. 
It  may  also  be  crystallized  from  absolute  alcohol,  but  on  boiling 
for  some  time  with  absolute  alcohol  it  is  converted  into  the 
mono-ethyl  ester  of  succhrc  acid. 

61.  Preparation  of  an  Ester — Ethyl  acetic  ester,  (Acetic  ester) 
O 

// 
CH3C— OC2H5.     (Ethyl  Ester  of  Ethanoic  Acid.) 

Literature — Geuther:  Jsb.  d.  chem.,  1863,  323;  Frankland,  Duppa:  Ann.. 
138,  205;  Markownikoff :  Ber.,  6,  1177;  Pabst :  Bull.  soc.  chim.,  33»  35O. 

25  cc.  alcohol. 

25  cc.  concentrated  sulphuric  acid. 

200  cc.  alcohol. 

200  cc.  glacial  acetic  acid. 

Place  in  a  250  cc.  distilling  bulb  25  cc.  of  alcohol,  and  25 
cc.  of  concentrated  sulphuric  acid.  Put  in  the  mouth  of  the 
bulb  a  stopper  bearing  a  separatory  funnel,  the  stem  of  which 
reaches  nearly  to  the  bottom  of  the  bulb,  and  a  thermometer 
which  dips  in  the  mixture.  (See  ethyl  ether,  p.  81.)  Connect 
with  a  condenser  and  heat  carefully  to  I3O°-I35°.  Run  in 
slowly  a  mixture  of  200  cc.  of  glacial  acetic  acid  and  200  cc. 
of  alcohol,  regulating  the  flow  and  the  flame  so  that  the  tem- 
perature remains  at  about  135°.  Shake  the  distillate  in  a  flask 
with  a  concentrated  sodium  carbonate  solution  till  it  no  longer  re- 
acts acid,  separate  the  aqueous  solution  by  means  of  a  separatory 
funnel,  add  a  solution  of  50  grams  of  calcium  chloride  in  50 


152  ORGANIC    CHEMISTRY 

grams  of  water,  shake,  and  separate  again,  to  remove  alcohol 
which  it  contains.  Dry  the  acetic  ester  by  allowing  it  to  stand 
over  night  with  a  little  fused  calcium  chloride,  and  fractionate. 
The  portion  boiling  at  72°-78°  is  nearly  pure.  For  use  in 
the  preparation  of  acetoacetic  ester  it  should  be  allowed  to 
stand  a  day  with  one-fifth  of  its  weight  of  granular  calcium 
chloride  and  filtered.  Yield  80-90  per  cent,  of  the  theory. 
Acetic  ester  boils  at  77°,  and  has  a  specific  gravity  of  0.9239 

o°  " ^  c;° 

at  — 5  ,   and  of  0.8300  at   — 1_  .     It   dissolves   in    17  parts  of 
4  4 

water  at  17.5°,  28  parts  of  the  ester  dissolve  one  part  of  water 
It  is  easily  saponified  by  boiling  with  alkalies,  and  is  slowly 
saponified  by  merely  standing  with  water. 

62.  Saponification  of  an  Ester  with  Sodium  Hydroxide  and  De- 
tection of  the  Alcohol  Formed. 

Literature — H.  Meyer:  Analyse  und  Konstitutionsermittelung  organ- 
ischer  Verbindungen,  p.  510;  Nernst :  Theoretical  Chemistry,  Translation 
of  the  4th  German  edition,  p.  550. 

2  grams  acetic  ester. 

15  cc.  sodium  hydroxide  (10  per  cent). 

Put  2  grams  of  acetic  ester  and  15  cc.  of  ten  per  cent, 
sodium  hydroxide  in  a  small  flask,  connect  with  an  upright 
condenser  and  boil  for 'fifteen  minutes,  cool,  transfer  to  a  5c 
cc.  distilling  bulb  and  distil  over  about  6  cc.  Put  the  distillate 
in  a  very  small  distilling  bulb  and  distil  about  3  cc.  To  the 
distillate  add  dry  potassium  carbonate  till  the  alcohol  separate? 
on  top.  Transfer  the  upper  layer  to  a  small  distilling  bulb 
and  determine  the  boiling-point,  boiling  it  with  a  very  small 
flame  and  using  as  small  a  distilling  bulb  as  possible.  See  pp.  26 
and  269.  .For  the  saponification  of  a  fat  see  48,  p.  121.  For 
the  saponification  of  a  cyanide  see  52  p.  133  and  140. 

63.  Preparation  of  an  Ester  of  a  Bibasic  Acid. — Ethyl  succinic 

CH2C02C2H5 
ester,     | 

CH2CO2C2H5 

Literature — Wegcr:  Ann.,  221,  89;  Fehling:  Ibid,  49>  186,  195;  Perkin : 
J.  Chem.  Soc.,  45,  SIS  (7##4)  ;  Crum  Brown,  Walker:  Ann..  261,  115. 


DERIVATIVES  OF  ACIDS  153 

loo  grams  succinic  acid. 

170  cc.  alcohol. 

5  cc.  concentrated  sulphuric  acid. 

In  a  300  cc.  flask  put  100  grams  of  succinic  acid,  170  cc. 
of  alcohol  and  5  cc.  of  concentrated  sulphuric  acid.  Heat 
for  two  hours  on  a  water-bath  with  an  upright  condenser  or 
condensing  tube.  Cool,  and  pour  into  a  large  flask  containing 
25  grams  of  sodium  bicarbonate  and  150  of  water.  Shake 
thoroughly,  and  separate  the  ester.  Wash  it  once  with  a  little 
water,  dry  as  directed  for  malonic  ester  (see  p.  138),  and  frac- 
tionate. Yield  good. 

Succinic  ethyl  ester  boils  at  2i7°-2i8°,  and  has  a  specific 
gravity  of  1.0475  at  25-5°- 

64.  Preparation  of  an  Ester  by  Means  of  Phosphorus  Pentachlo- 
ride  and  Alcohol.— Benzoic  ethyl  ester,  C6H5CO2C2H5. 

Literature — Baeyer:  Ann.,  245,  140;  Liebig:  Ibid,  65,  351;  E.  Fischer, 
Speier:  Ber.,  28,  1150,  3255. 

10  grams  benzoic  acid. 

21  grams  phosphorus  pentachloride. 

50  cc.  alcohol. 

Put  in  a  small  flask  10  grams  benzoic  acid,  and  21  grams  of 
phosphorus  pentachloride.  Connect  with  a  tube  which  will 
deliver  the  hydrochloric  acid  evolved  just  above  the  surface  of 
water  in  a  bottle.  Warm  on  a  water-bath  till  all  is  liquid.  Cool 
and  pour  carefully  into  50  cc.  of  alcohol.  Cool  thoroughly,  add 
100  cc.  of  water  and  enough  ether  to  bring  the  benzoic  ester 
to  the  surface.  Separate,  wash  with  a  solution  of  sodium  carbo- 
nate to  remove  acid,  dry  the  ethereal  solution  by  allowing  it  to 
stand  for  several  hours  with  dry  potassium  carbonate,  pour 
off,  or  filter,  and  distil  from  a  small  distilling  bulb. 

Other  methods  of  preparing  benzoic  ester  are  more  suitable, 
and  this  method  is  only  given  as  an  illustration  of  a  method 
which  is  quite  generally  applicable.  The  yield  is  almost  quan- 
titative, if  care  is  used. 

Benzoic  ester  boils  at  211°,  and  has  a  specific  gravity  of 
1.0502  at  1 6°. 


154  ORGANIC    CHEMISTRY 

65.  Preparation  of  the  Benzoyl  Derivative  of  a  Phenol — Schot- 

O 

// 
ten — Baumann  Reaction. — Phenyl  benzoate,  C6H5 — C — O — C6H5. 

Literature — Baumann:  Ber.,  19,  3218;  Udranszky  and  Baumann:  Ibid, 
21,  2744;  Hinsberg:  Ibid,  23,  2962;  Schotten :  Ibid,  17*  2545. 

Dissolve  about  one-half  gram  of  phenol  in  5  cc.  of  water, 
add  three-fourths  gram  of  benzoyl  chloride  and  a  little  caustic 
soda,  enough  so. that  the  solution  remains  alkaline  after  warm- 
ing and  shaking  till  the  odor  of  benzoyl  chloride  has  disappear- 
ed. On  cooling  and  standing  the  phenyl  benzoate  solidifies, 
and,  after  filtering  off  and  washing,  may  be  crystallized  from 
a  little  alcohol.  It  melts  at  69°. 

This  reaction,  which  is  generally  applicable  to  alcohols,  phen- 
ols, and  to  primary  and  secondary  amines,  and  in  which  acetic 
anhydride,  sulphonechlorides  and  other  similar  compounds  may 
be  used  instead  of  benzoyl  chloride,  is  especially  useful  in  con- 
verting liquid  or  easily  soluble  bodies  into  solid,  difficulty  solu- 
ble derivatives  for  purposes  of  identification. 

66.  Preparation  of  the  Ester  of  a  Hydroxy  Acid  and  of  an 
Acetyl  Derivative. — Di-acetyl  tartaric  ethyl  ester, 

C02C2H6 

CH  —  OC2H3O 
CH  -  OC2H30 

C02C2H5. 

Literature.— Landolt :  Ann.,  189,  324;  Anschiitz :  Ber.,  18,  1397;  Wislice- 
nus:  Ann.,  129,  184;  Perkin :  A  Supl.,  5,  285;  J.  Chem.  Soc.,  51,  369 
(1887);  E.  Fischer:  Ber.,  28,  3255. 

25  grams  tartaric  acid. 

1 20  cc.  absolute  alcohol. 

i  gram  hydrochloric  acid  gas. 

Put  25  grams  of  tartaric  acid  in  a  200  cc.  distilling  bulb,  add 
1 20  cc.  of  absolute  alcohol,  and  pass  into  the  bulb  about  one 
gram  of  hydrochloric  acid  gas.  The  gas  may  be  generated  in  a 
small  flask  from  salt  and  concentrated  sulphuric  acid  diluted 


DERIVATIVES  OF  ACIDS  155 

with  one-fourth  of  its  volume  of  water,  or  by  dropping  concen- 
trated sulphuric  acid  into  commercial  hydrochloric  acid,  and 
the  amount  can  be  determined  by  placing  the  bulb  in  a  beaker 
on  one  pan  of  a  balance,  which  is  sensitive  to  about  one-tenth 
gram.  Close  the  side  tube  of  the  bulb  with  a  bit  of  rubber  tubing 
and  a  glass  rod,  and  place  in  the  mouth  of  the  bulb  a  stopper 
and  tube  to  act  as  an  ,air  condenser.  Heat  for  2  to  3  hours 
on  a  water-bath,  inclining  the  bulb  in  such. a  manner  that  the 
vapors  which  condense  in  the  side  tube  will  run  back  into  the 
bulb.  Adjust  a  capillary  tube  and  stopper,  and  a  second  bulb  to 
collect  the  distillate,  as  on  p.  171  and  distil  the  excess  of  alcohol 
and  the  water  formed  under  gradually  diminishing  pressure,  and 
tmally  dry  for  fifteen  minutes  under  as  k.\v  a  pressure  as  can  be 
secured  and  with  the  bulb  immersed  in  a  boiling  water-bath. 
Add  80  cc.  of  absolute  alcohol,  and  one  gram  of  hydrochloric 
acid,  and  heat  as  before  with  an  air  condenser  for  two  hours. 
By  the  removal  of  the  water  formed  by  the  esterification,  and  a 
second  treatment  with  fresh  alcohol  a  much  more  -  complete 
conversion  can  be  secured.  Distil  the  alcohol  and  water  as  be- 
fore and  then  distil  from  an  oil-bath  or  with  the  free  flame 
under  as  low  a  pressure  as  can  be  secured  and  with  a  thermom- 
eter (see  p.  171).  The  portion  boiling  a.t  i6o°-i8o°  under  30 
mm.  pressure  will  consist  of  nearly  pure  di-ethyl  tartaric  ester. 
Yield  23-26  grams. 
The  ester  boils  at 

280°   under   a   pressure  of   760  mm. 

232°   under   a  pressure  of   197   mm. 

162°    under  a  pressure  of      19  mm. 

157°   under   a  pressure  of      11   mm. 
It  has  a  specific  gravity  of  1.2059  at  20° 
3  grams  di-ethyl  tartaric  ester. 
5  grams  acetic  anhydride. 
30  cc.  sodium  hydroxide  (10  per  cent.). 

Place  in  a  small  flask  3  grams  of  di-ethyl  tartaric  ester,  add 
five  grams  of  acetic  anhydride  and  then,  in  small  portions,  with 
constant  shaking,  30  cc.  of  a  10  per  cent,  solution  of  sodium 


156  ORGANIC    CHEMISTRY 

hydroxide.  As  soon  as  the  odor  of  the  acetic  anhydride  has 
disappeared,  filter  off  the  acetyl  derivative,  if  it  solidifies,  wash 
it  with  water  and  recrystallize  it  from  alcohol,  dissolving  in 
a  very  little  hot  alcohol,  and  adding  water  till  the  solution  begins 
to  become  turbid. 

If  the  acetyl  compound  fails  to  solidify  at  first,  it  will  usually 
do  so  on  standing  in  a  cool  place  for  a  day  or  two.  If  somo  of 
the  crystallized  compound  is  at  hand,  the  addition  of  a  crystal 
will  be  of  service. 

Di-acetyl  tartaric  ethyl  ester  melts  at  67°,  and  boils  at  291°- 
292°  under  727  mm.,  or  at  229°-23O°  under  100  mm. 

Very  considerable  historical  interest  attaches  to  the  substance, 
because  by  means  of  it  the  structure  of  tartaric  acid  was  first 
clearly  established. 

67.  Preparation  of  an  Amide  by  Heating  the  Ammonium  Salt 
of  an  acid. — Acetamide,  CH3 — CONH2. 

Literature.— Letts :  Ben,  5,  669;  Hofmann :  Ibid,  15,  9?8;  v.  Nencki, 
Leppert:  Ibid,  6,  903;  J.  Schultze:  J.  prakt.  Chem.,  (1883),  N,  F.,  27,  514 

50  grams  glacial  acetic  acid. 

55  to  60  grams  ammonium  carbonate. 

Warm  50  grams  of  acetic  acid  gently  in  a  porcelain  dish  and 
add  powdered  ammonium  carbonate  till  a  little  of  the  mixture,  on 
dilution  with  water,  shows  an  alkaline  reaction  with  litmus. 
Prepare  two  sealing  tubes  about  2  to  2.5  centimeters  in  internal 
diameter,  and  with  walls  2  to  3  mm.  thick.  In  closing  the  ends 
of  the  tubes,  and  also  in  sealing  after  they  have  been  filled,  the 
glass  must  be  so  thoroughly  softened  as  to  sink  together  some- 
what, and  must  not  be  drawn  so  rapidly  as  to  become  thin  at 
any  point.  Warm  the  sealing  tubes  gently  over  the  flame,  and 
heat  the  ammonium  acetate  till  it  becomes  liquid.  Transfer  it 
to  the  tubes,  using  a  thistle  tube  or  funnel  with  a  long  stem  so 
that  the  tubes  are  not  wet  near  the  point  where  they  are  to  be 
sealed.  The  tubes,  when  sealed,  should  not  be  more  than  three- 
fourths  full.  Seal  the  tubes  carefully,  and  when  cold  put  them  in 
a  bomb  oven  and  heat  for  five  hours  at  22O°-23O°.  Cool.  Open 
the  tubes  and  transfer  the  mixture  to  a  distilling  bulb  and  subject 


DERIVATIVES  OF  ACIDS  157 

it  to  fractional  distillation,  using  an  air  condensing  tube  (see 
p.  26).  Collect  the  portion  boiling  at  i8o°-23O°  in  a  beaker. 
Cool  thoroughly,  and  spread  on  porous  porcelain  to  remove 
liquid  impurities.  The  portion  remaining  will  be  nearly  pure 
acetamide.  The  pure  compound  may  be  obtained  by  crystalliz- 
ation from  benzene  or  chloroform.  Yield  about  25  grams. 

Pure  acetamide  consists  of  colorless,  odorless,  rhombohedral 
crystals,  which-melt  at  82°.  It  boils  at  222°.  »It  is  easily  solu- 
ble in  alcohol  and  in  water,  difficultly  soluble  in  ether  and  ben- 
zene. 

Acetamide  is  easily  saponified  by  alkalies.  It  is  converted 
into  methylcyanide  (acetonitrile)  by  warming  for  a  short  time 
with  phosphorus  pentoxide  and  distilling.  An  aqueous  solution 
of  acetamide  dissolves  mercuric  oxide  with  the  formation  of  the 
compound,  (CH3CONH)2Hg.  The  hydrogen  of  the  amide 
group  may  also  be  replaced  by  bromine  or  by  other  halogen 
atoms.  Acetamide  forms  unstable  salts  with  hydrochloric  acid 
and  with  nitric  acid. 

68.  Preparation  of  an  Acyl  Derivative  of  an  Amine. — Acet- 
anilide,  C6H5NH.C2H3O. 

Literature — Gerhardt :  Ann.,  87,  164;  Williams:  Ibid,  131,  288;  Witt: 
Dissertation,  (Zurich,  1875),  12,  Williams:  J.  Chem.  Soc.,  17,  106,  (1864). 

25  grams  aniline. 

35  grams  glacial  acetic  acid. 

Put  in  a  200  cc.  flask  25  grams  of  aniline  and  35  grams  of 
glacial  acetic  acid.  Place  in  the  mouth  of  the  flask  a  stopper 
bearing  a  tube  one  cm.  in  diameter  and  50  cm.  long.  Heat  on 
a  thin  asbestos  paper  on  a  wire  gauze,  and  adjust  the  flame  so 
that  the  vapors  of  the  acetic  acid  condense  about  two-thirds  of 
the  way  up  the  tube.  As  water  is  formed  during  the  reaction, 
it  will  gradually  escape  from  the  top  of  the  tube,  and  this  hasten- 
es  the  reaction.  If  the  apparatus  cannot  be  conveniently  placed 
in  a  hood,  the  top  of  the  tube  should  be  bent  over,  and  a  flask 
placed  under  it  to  collect  the  dilute  acid  which  escapes.  After 
boiling  for  4  to  5  hours,  pour  carefully,  with  stirring,  into  400 
cc.  of  water,  filter  when  cold,  and  recrystallize  from  hot  water. 


158  ORGANIC    CHEMISTRY 

dilute  alcohol,  or  from  benzene.  Yield  about  80  per  cent,  of  the 
theory. 

Acetanilide  (known  in  medicine  as  antifebrin)  melts  at  116°, 
and  boils  at  304°.  It  dissolves  in  189  parts  of  water  at  6°.  It 
is  easily  soluble  in  hot  water,  alcohol,  ether,  and  benzene.  It 
may  be  saponified  either  by  boiling  with  caustic  potash  or  con- 
centrated hydrochloric  acid. 

69.  Preparation  of  an  Amide  from  the  Chloride  of  an  Acid.— 

/NH2 

Urea,   CO<(  ,   Carbamide. 

XNH2 

Literature.  —  Wohler:  Berz.  Jsb.,  12,  266  (1828};  Natanson  :  Ann.,  98, 
289;  Basarow;  J.  prakt.  Chem,  [2],  i,  283;  Mixter:  Am.  Chem.  J.,  4» 
35;  Millon:  Ann.  chim.  phys.,  [2],  8,  235;  Schmidt:  Ber.,  10,  191  ;  Duggan  : 
Am.  Chem.  J.,  4,  47;  Schmidt:  Z.  anal.  Chem.,  i,  242. 

10  cc.  solution  of  phosgene  in  toluene  (20  per  cent.). 

15  cc.  ammonia  (0.96). 

Put  in  a  small  flack  15  cc.  of  ammonia  and  add  in  three  or  four 
portions,  shaking  and  cooling  after  each  addition,  10  cc.  of  a 
twenty  per  cent,  solution  of  carbonyl  chloride,  COC12  (phos- 
gene), in  toluene.  The  solution  should  now  react  alkaline.  Pour 
the  mixture  into  a  porcelain  dish,  and  evaporate  to  dryness  on 
the  water-bath.  Put  the  residue  into  a  dry  test-tube,  add  about 
10  cc.  of  alcohol,  and  boil.  Cool,  pour  off  through  a  filter,  and 
repeat  the  same  treatment  twice.  Evaporate  the  alcoholic  solu- 
tion to  dryness.  The  residue  will  now  consist  mainly  of  urea 
with  a  little  ammonium  chloride.  About  one  gram  should  be 
obtained.  Crystallize  from  a  little  amyl  alcohol. 

Urea  crystallizes  in  long  prisms  or  thick  needles.  It  melts  at 
132°.  It  is  easily  soluble  in  water.  100  parts  of  alcohol  dissolve 
5.06  parts  at  19.5°.  From  not  too  dilute  aqueous  solutions  it  is 


/2 
precipitated  in  the  form  of  the  nitrate,  CO^  ,  on  the 

\NH2HNO3 
addition  of  nitric  acid.     The  nitrate  is  very  difficultly  soluble  in 

/NH, 

nitric  acid,  and  is  converted  into  nitrourea,   CO\  ,    by 


NHNO2 


DERIVATIVES  OF  ACIDS  159 

cold  concentrated  sulphuric  acid.  (See  p.  94).  Urea  forms  dou- 
ble compounds  with  many  salts  and  metallic  oxides,  and,  also, 
compounds  in  which  its  hydrogen  is  replaced  by  metals.  It  is 
decomposed  by  alkaline  hypobromites  with  liberation  of  nitrogen, 
a  property  used  for  its  quantitative  determination. 

Concentrated  solutions  of  alkalies  decompose  it  on  boiling, 
with  the  formation  of  a  carbonate  and  ammonia.  Acids  decom- 
pose it  more  rapidly. 

70.  Preparation  of  an  Amide  by  means  of  Phosphorus  Penta- 
chloride  and  Ammonia. — Phenyl  sulphonamide,  C6H5SO2NH2. 

Literature — Mitscherlich :  Ann.  phys.  (Pogg.),  3*»  283,  631;  Stenhouse: 
Ann.,  140*  284 ;  Gattermann :  Ber.,  24,  2121 ;  Michael,  Adair :  Ber.,  10, 
585;  Gerhardt,  Chancel :  J.,  1852,  434;  v.  Meyer,  Ador :  Ann.,  i59»  n; 
Limpricht:  Ibid,  221,  206. 

100  cc.  fuming  sulphuric  acid  (sp.  gr.  1.87). 
50  cc.  benzene 

350  cc.  water. 

50  grams  acid  sodium  carbonate. 

loo  grams  salt. 

20  grams  crude  sodium  benzene  sulphonate. 
20  grams  phosphorus  pentachloride. 

70  cc.  ammonia  (sp.  gr.  0.90). 

To  loo  cc.  of  fuming  sulphuric  acid,  containing  5  to  8  per 
cent,  of  the  anhydride  (sp.  gr.  1.87  at  15°),  in  a  300  cc.  flask, 
add,  in  small  portions,  50  cc.  of  benzene,  shaking  vigorously 
after  each  addition  and  keeping  the  temperature  below  50°  by 
occasional  cooling.  When  the  benzene  has  all  dissolved,  pour 
slowly  into  350  cc.  of  water,  cool,  and  filter  from  any  diphenyl 
sulphone,  (C6H5)2SO2,  which  separates.  Partly  neutralize  the 
acid  by  adding,  carefully,  50  grams  of  acid  sodium  carbonate 
(baking  soda),  then  add  100  grams  of  common  salt,  warm  till 
it  dissolves,  filter  and  cool,  with  stirring.  As  soon  as  the  sodium 
benzene  sulphonate  has  separated  completely,  filter  on  a  plate  and 
suck  dry.  Moisten  with  a  saturated  solution  of  salt  and  suck 
dry  again.  Dry  the  salt  on  a  plate  of  porous  porcelain.  Yield 


J6O  ORGANIC    CHEMISTRY 

40  to  50  grams  of  the  salt.  The  salt  can  be  crystallized  from  al- 
cohol if  desired,  but  is  already  pure  enough  for  most  purposes. 
/Place  in  a  100  cc.  flask  20  grams  of  phosphorus  pentachloride 
(weigh  in  the  hood  and  avoid  exposure  to  the  air  as  far  as  pos- 
sible), add  20  grams  of  crude  sodium  benzene  sulphonate,  dried 
at  120°,  close  the  flask  with  a  perforated  rubber  stopper  bearing 
a  tube  which  will  deliver  the  hydrochloric  acid  evolved  just 
above  the  surface  of  water  in  a  bottle  or  flask.  Warm  on  the 
water-bath  as  Pong  as  hydrochloric  acid  is  evolved.  Cool.  Pour 
the  contents  of  the  flask,  in  small  portions,  into/yo  cc.  of  am- 
monia (0.90  sp.  gr.)  contained  in  a  200  cc.  flask]"*  cooling  thor- 
oughly after  each  addition.  Filter,  wash  with  cold  water,  and 
crystallize  from  hot  water  or  from  dilute  alcohol.  Yield  12  to 
15  grams. 

If  benzene  sulphonechloride  is  desired,  th^T  liquid  product  ob- 
tained by  the  action  of  the  pentachloride  on  sodium  benzene  sul- 
phonate may  be  poured  in  small  portions  into  200  cc.  of  cold 
water,  and  shaken  with  the  latter  for  some  time  to  decompose 
the  phosphorus  oxychloride,  the  sulphonechloride  taken  up  with 
ether,  and  after  drying  with  calcium  chloride  and  distilling  off 
the  ether,  distilled  unc^er  diminished  pressure. 

Benzene  sujphonechloride  melts  at  145°  and  boils  with  decom- 
position at  246°.  Under  10  mm.  pressure  it  boils  at  120°.  It 
has  a  specific  gravity  of  1.378  at  23°. 

It  may  be  used  to  distinguish  the  three  classes  of  amines 
(Hinsberg:  Ber.,  23,  2963).  With  primary  amines  it  gives  alkyl- 
sulphonamides,  CfiH5SO2NHR,  which  are  soluble  in  alkalies,  with 
secondary  amines  it  gives  dialkyl-sulphonamides  C6H5SO2NRR', 
which  are  insoluble  in  alkalies,  and  with  tertiary  amines  it  does 
not  react.  The  compounds  with  primary  and  secondary  amines 
may  usually  be  prepared  by  the  Schotten-Baumann  reaction. 

Benzene  sulphonamide  crystallizes  in  needles  from  water,  or 
in  leaflets  from  alcohol.  Both  melt  at  I47°-I48°.  (Hybbeneth 
gives  156°.)  It  is  easily  soluble  in  alcohol  and  ether,  difficultly 
soluble  in  cold  water.  The  hydrogen  of  the  amide  group  can  be 
replaced  by  metals,  hence  the  sulphonamides  are  soluble  in  alka- 
lies, and  some  of  them  are  quite  soluble  in  a  solution  of  sodium 


DERIVATIVES  OF  ACIDS  l6l 

carbonate.     It  is  probable  that  the  amide  dissolves  in  the  "pseudo" 

/ONa 
form,    C6H5SO<f 


71.  Phenyl  Cyanide,  C6H5CN.     Benzonitriie. 

Literature  —  Laurent,  Gerhardt  :  Jsb.  d.  chem.,  1849,  327  ;  Wohler  :  Ann.. 
192,  362;  Henry:  Ber.,  2,  307;  Letts:  Ibid,  5»  673;  Merz:  Z.  Chem.,  1868, 
33;  Merz,  \\"eith:  Ber.,  8,  918;  10,  749;  Lach  :  Ibid,  i?»  1571;  Sandmeyer  : 
Ibid.  17,  2653. 

15  grams   benzoyl  chloride. 
60  cc.  ammonia  (sp.  gr.  0.96). 
10  grams  benzamide. 
15  grams  phosphorus  pentoxicle. 

Put  in  a  flask  15  grams  of  benzoyl  chloride,  add  60  cc.  of  am- 
monia (10  per  cent.),  and  shake  vigorously  till  the  chloride  dis- 
solves, which  should  take  onjy  a  minute  or  two.  Cool  at  once 
and  thoroughly.  Filter  off  the  benzamide  which  separates,  wash 
it  till  free  from  ammonium  chloride,  and  dry  in  the  air  or  on  the 
water-bath,  n  grams  of  pure  benzamide  should  be  obtained. 

Put  in  a  small  distilling  bulb  10  grams  of  benzamide,  and  15 
grams  of  phosphorus  pentoxide,  and  mix  as  thoroughly  as  pos- 
sible by  shaking.  Heat  in  an  oil-bath  at  22O°-24O°  as  long  as 
phenyl  cyanide  distils  over.  A  condenser  is  not  necessary,  but 
the  cyanide  may  be  collected  in  a  small  flask  or  test-tube  as  it 
distils.  Yield  6  to  7  grams. 

Most  amides  lose  water  when  heated  with  phosphorus  pent- 
oxide,  and  are  converted  into  the  corresponding  cyanides  or  ni- 

triles. 

Benzamide  crystallizes  in  monoclinic  plates,  or  in  leaflets  which 
melt  at  128°.  It  is  difficultly  soluble  in  cold  water,  easily  solu- 
ble in  alcohol. 

Phenyl  cyanide  is  a  colorless  oil  which  solidifies  in  a  freezing 
mixture  of  ether  and  solid  carbon  dioxide,  and  melts  at  —  17°. 
It  boils  at  190.7°.  and  has  a  specific  gravity  of  1.0084  at  16.8°. 
n 


l62  ORGANIC    CHEMISTRY 

72.  Uric  Acid. 

NH  —  CO  N          COH 

/  I  I 

CO  C  —  NHV  COH    C  —  NH 

\  II  >CO,  or     ||  ||          \COH 

NH-C--NH/  Jj  _   c-N^ 

Literature — Uebig  and  Wohler :  Ann.,  26,  245  ;  Wohler  :  Ann.,  70,  229 ; 
88,  ioo ;  Arppe:  Ibid,  87,  237;  Goesmann :  Ann.,  99,  374;  Gibbs :  Chem.  Z. 
1869,  729;  Am.  J.  Sci.,  48,  215  (1869)  \  Ann.  Supl.,  Bd.,  7,  324;  Horbac- 
zewski:  Ber.,  15*  2678;  Behrend  u.  Roosen :  Ber.,  21,  999;  Ann.,  251, 
235,  Formanek:  Ber.,  24,  3419;  Zabelin :  Ann.  Supl.  Bd.,  2,  313;  Fresen- 
ius :  Z.  anal.  Chem.,  2,  456;  Salkowski :  Ibid,  16,  373;  E.  Fischer:  Ber., 
X7,  1785;  30,  549. 

i  liter  urine. 

25  cc.  concentrated  hydrochloric  acid. 

Add  to  one  liter  of  urine  25  cc.  of  concentrated  hydrochloric 
acid  and  allow  to  stand  in  a  cool  place  for  two  days.  Decant 
the  liquid  from  the  crystals  of  uric  acid  and  wash  them  by  de- 
cantation.  Transfer  to  a  test-tube,  dissolve  in  the  smallest  possi- 
ble amount  of  5  per  cent,  sodium  hydroxide,  add  a  drop  of  a 
solution  of  potassium  pyrochromate  and  boil,  then  add  a  little 
bone-black,  shake,  and  filter.  Precipitate  the  uric  acid  with  hy- 
drochloric acid,  allow  to  separate  completely,  filter,  and  wash. 
In  working  with  larger  amounts  of  uric  acid  the  amount  of  the 
pyrochromate  should  be  five  per  cent,  of  that  of  the  uric  acid, 
and  after  the  second  precipitation  the  uric  acid,  which  is  slightly 
yellow,  should  be  warmed  several  times  with  strong  hydrochloric 
acid,  till  it  is  perfectly  white.  (Gibbs:  Loc.  cit.)  * 

The  yield  from  one  liter  of  urine  will  usually  be  one-half  a 
gram  or  less. 

Uric  acid,  forms  a  white  crystalline  powder,  which  is  almost 
insoluble  in  water,  alcohol,  and  ether.  It  dissolves  in  alkalies 
with  the  formation  of  salts  in  which  two  atoms  of  hydrogen 
are  replaced  by  the  metal.  Carbon  dioxide  precipitates  from 
such  solutions  difficultly  soluble  acid  salts,  a  property  used  in 
the  preparation  of  the  acid  from  guano.  It  is  precipitated  from 
its  solutions  by  an  ammoniacal  solution  of  silver  nitrate.  If  a 


DERIVATIVES  OF  ACIDS  163 

little  uric  acid  is  moistened  with  nitric  acid,  and  the  solution 
evaporated  on  the  water-bath,  the  residue  dissolves  in  ammonia  to 
an  onion-red  solution,  which  becomes  violet  on  adding  sodium 
hydroxide  ("murexide  reaction"). 

Nitric  acid  oxidizes  uric  acid  to  alloxan, 

/NH  —  COX 

CO/  >C(OH).,  +  3H.,0, 

XNH  —  CO/ 

and  the  latter  is  decomposed  by  alkalies  into  urea  and  dihydroxy- 

XC02H 
/  OH 

malonic  acid  (mesoxalic  acid),    C<^TJ 

v      \Jl~L 

XC02H 

The  structural   formulas  given  above  are  based,  in  part,  on 
these  reactions. 


Chapter  IX 

HYDROXY  AND  KETONIC  ACIDS 

Hydroxy  acids  may  be  prepared  by  several  of  the  methods 
used  for  the  preparation  of  alcohols,  as  for  instance:  by  the 
treatment  of  a  halogen  derivative  of  an  acid  with  water  or  an 
alkali,  or  with  silver  oxide  and  water;  by  the  treatment  of  an 
amino  acid  with  nitrous  acid ;  or  by  the  oxidation  of  an  unsat- 
urated  acid  with  potassium  permanganate,  giving  a  dihydroxy 
acid.  (See  pp.  64,  65.) 

Ortho-  and  para-hydroxy  acids  may  be  prepared  from  phenols 
by  heating  a  sodium  or  potassium  salt  of  a  phenol  with  carbon 
dioxide  (Kolbe's  Synthesis).  It  was  formerly  supposed  that  a 
phenyl  sodium  carbonate  is  at  first  formed  but  Tijmstra  has 
shown  (Ber.,  38,  1375)  that  the  reaction  consists  at  first  in  the 
direct  addition  of  the  phenolate  to  carbon  dioxide : 

/ONa 
C6H5ONa  +  CO2  —  C6H  / 

XC02H 

If  the  reaction  is  carried  out  in  an  autoclave  under  pressure 
it  may  be  made  nearly  complete,  while  at  atmospheric  pressure 
the  compound  formed  reacts  with  another  molecule  of  the  phenol- 
ate  and  phenol  distils  away : 

ONa  /ONa 

+   C6H5ONa.-  C6H4<(  f  C6H5OH. 

CO2H  xCO2Na 

With  sodium  phenolate.  the  carboxyl  enters  chiefly  in  the  ortho 
position,  giving  salicyclic  acid,  while  with  potassium  phenolate 
para-hydroxy  benzoic  acid  is  formed. 

Cyanhydrines  may  be  prepared  by  the  addition  of  nascent  hy- 
drocyanic acid  to  an  aldehyde  or  ketone.  The  cyanhydrine  may 
be  saponified  to  an  a-hydroxy  acid. 

OH 

-f-  HCN  ==  R  —  CH  -  CN. 


HYDROXY    AND    KETONIC    ACIDS  165 


/OH  , 

R  —  CH/          4-  HC1  -h  2H,O        R  —  CH<  -f-  NH4C1. 

XCN  XC02H 

Under  the  influence  of  sodium  ethylate  some  esters  may  be 
condensed  to  form  esters  of  ketonic  acids,  of  which  acetoacetic 
ester  and  succinylosuccinnic  ester  may  be  considered  types  (see 
p.  109). 

When,  a  compound  contains  a  methylene  (CH2)  or  methine 
(CH)  group  which  is  combined  with  two  carboxyl  groups,  as  in 
acetoacetic  ester  or  malonic  ester  or  between  a  carboxyl  and  a 
cyanogen  group,  as  in  cyanacetic  ester  it  will  usually  react  with 
sodium  ethylate  in  the  "enol"  form  giving  a  sodium  salt  which 
will,  in  turn,  add  an  alkyl  group  in  such  a  manner  as  to  practi- 
cally replace  the  hydrogen  of  the  methylene  or  methine  group  by 
the  allyl  radical  (see  p.  in).  The  decompositions  of  acetoacetic 
ester  and  of  malonic  acid  and  their  derivations  have  already  been 
considered  (p.  112). 


73.  Preparation  of  a  Hydroxy  Acid  by  Treatment  of  the 
Sodium  Salt  of  a  Phenol  with  Carbon  Dioxide  (Kolbe's  Syn- 

/C02H     (i) 
thesis). — Salicylic  acid,  C6H4/  (0-hydroxybenzoic 

X)H         (2) 
acid). 

Literature — Gerhardt :  Ann.,  45>  21;  Kohler :  Ber.,  12,  246;  Earth:  Ann., 
J54i  360;  Hiibner:  Ibid,  165,  i ;  Gerland :  Ibid,  86,  147;  Kolbe,  Lautemann : 
Ibid,  ii5i  201;  Kolbe:  J.  prakt.  Chem.,  [2],  10,  93;  Hentschel:  Ibid, 
[2],  27,  41-;  Schmitt:  Ibid,  [2],  3*,  407;  Reimer,  Tiemann :  Ber.,  9,  423, 
824;  10,  213;  Tijmstra:  Ibid,  38,  1375. 

12.5  grams  sodium  hydroxide. 
30  grams  phenol. 
20  cc.  water. 

Dissolve  12.5  grams  of  sodium  hydroxide  in  20  cc.  of  water 
in  a  porcelain,  or  better,  in  a  nickel  dish.  Add,  in  portions,  30 
grams  of  crystallized  phenol.  Fasten  the  dish  firmly  by  means 
of  a  clamp  and,  with  the  burner  in  the  hand  and  in  constant 
motion,  heat  and  stir  carefully  till  a  thoroughly  dry  powder  is  ob- 


1  66  ORGANIC    CHEMISTRY 

tained.  Transfer  this  at  once  to  a  100  cc.  distilling  bulb,  or  re- 
tort, place  the  latter  in  an  oil-bath  and  pass  through  it  a  current 
of  dry  hydrogen,  while  the  bath  is  heated  to  140°  for  half  an 
hour. 

The  salt  should  be  so  dry  that  it  does  not  sinter  together 
during  this  part  of  the  process.  Allow  the  oil-bath  to  cool  to 
110°,  and  pass  a  current  of  dry  carbon  dioxide  through  the  bulb 
for  one  hour.  Then  allow  the  temperature  to  rise  at  the  rate  of 
about  20°  an  hour  till  a  temperature  of  200°  is  reached,  and 
heat  finally  for  an  hour  at  that  temperature,  continuing  a  slow 
current  of  carbon  dioxide.  The  side  tube  of  the  distilling  bulb 
should  be  heated  gently,  once  in  a  while,  to  melt  the  phenol 
which  distills  over.  Cool,  rinse  the  phenol  out  of  the  side  tube, 
dissolve  the  residue  in  the  distilling  bulb  in  water,  filter,  if 
necessary,  and  precipitate  the  salicylic  acid  from  the  filtrate  with 
concentrated  hydrochloric  acid.  Recrystallize  from  water,  us- 
ing a  little  bone-black,  if  the  acid  is  colored.  Yield  5  to  10 
grams. 

The  potassium  phenolate  reacts  at  150°  in  the  same  manner  as 
the  sodium  salt,  but  at  220°  it  gives  the  parahydroxybenzoate 
instead  of  the  salicylate. 

This  synthesis  is  quite  general  in  its  application,  and  deriva- 
tives of  phenol  react  in  a  manner  similar  to  phenol  itself. 

Salicylic  acid  crystallizes  in  white  needles  which  melt  at  156°. 
The  solution  gives  an  intense  violet  color  with  ferric  chloride, 
a  reaction  characteristic  of  all  orthohydroxy  acids  of  the  benzene 
series.  Salicylic  acid  is  often  used  in  articles  of  food  on  account 
of  its  antiseptic  properties,  and  the  reaction  with  ferric  chloride 
is  made  use  of  in  its  detection. 

74.  Preparation    of    an  a-Hydroxy    Acid    from    an    Aldehyde, 


through  the  Cyanhydrine.—  Mandelic  acid,  C6H5C—  CO2H  (phen- 

\H 
ethylolic  acid). 

Literature  —  Winckler:  Ann.,  18,  310;  Spiegel:  Ber.,  14,  239;  Engler, 
Wohrle:  Ibid,  20,  2202;  Wallach  :  Ann.,  i93»  38;  Louguinine  u.  Naquet  : 
Ibid,  i39,  299;  Miiller:  Ber.,  4,  980. 


HVDROXY    A  NIT   KE)TONIC    ACIDS  l6/ 

20  grams  benzaldehyde. 

13  grams  potassium  cyanide. 

15.3  cc.  hydrochloric  acid   (sp.  gr.  1.19). 

Put  into  a  small  flask  13  grams  (i  mol.)  of  pure  potassium 
cyanide,  and  20  grams  (i  mol.)  of  freshly  distilled  benzaldehyde. 
Place  the  flask  in  ice-water,  and  drop  in  slowly  from  a  burette 
7  grams  (i  mol.)  of  hydrochloric  acid.  This  will  be  14.3  cc.  of 
an  acid  of  sp.  gr.  1.20,  or  15.3  cc.  of  an  acid  of  sp.  gr.  1.19. 
During  the  addition  of  the  acid  shake  frequently,  and  allow  the 
mixture  to  stand  for  one  hour  after  all  has  been  added.  Then 
pour  into  150  cc.  of  cold  water.  Separate  the  cyanhydrine  from 
the  solution,  and  wash  twice  with  water  (see  51,  p.  127).  Trans- 
fer the  nitrile  to  a  porcelain  dish,  add  50  cc.  of  concentrated  hy- 
drochloric acid,  and  evaporate  on  a  sand  bath  till  crystals  begin 
to  separate  on  the  upper  surface  of  the  liquid.  Dissolve  the 
residue  in  about  100  cc.  of  warm  water,  filter  from  any  oil  which 
remains,  and  extract  the  mandelic  acid  from  the  filtrate  with 
ether. 

In  extracting  with  ether,  especially  when,  as  in  this  case,  the 
substance  to  be  extracted  is  easily  soluble  in  water,  the  solution 
should  be  as  concentrated  as  possible.  It  is  also  an  advantage,  in 
many  cases,  to  add  salt  or  ammonium  sulphate  to  the  solution 
which  is  to  be  extracted.  This  lessens  the  solubility  of  the  ether 
in  the  solution  and  also  of  the  water  in  the  ether.  In  extracting, 
put  the  solution  to  be  extracted  into  a  separatory  funnel,  which 
should  be  chosen  of  such  size  as  to  be  nearly  filled.  Add,  ac- 
cording to  the  ease  with  which  the  substance  is  extracted  from 
the  solution  and  according  to  the  volume  of  the  latter,  10-50  cc. 
of  ether.  When  a  substance  is  easily  extracted,  use  but  little 
ethei  ;  if  extracted  with  difficulty,  a  larger  amount;  and  the  ex- 
traction must,  in  such  a  case,  be  many  times  repeated.  These 
rules  follow  from  the  law  for  the  division  of  a  substance  be- 
tween two  immiscible  solvents,  which  is,  that  the  amounts  re- 
tained in  a  unit  volume  of  each  have  a  fixed  ratio,  independent- 
ly of  the  volume  of  each.  The  ratio  is  called  the  partition 
coefficient,  and  in  the  present  case  expresses  the  amount  of  sub- 


1  68  ORGANIC    CHEMISTRY 

stance  contained  in   100  cc.  of  the  aqueous  solution  divided  by 
the  amount  contained  in    100  cc.   of  the  ethereal   solution. 

Expressed  mathematically,  let 

.r0  =  amount  of  substance  present. 

x^  —  amount  of  substance  retained  by  the  water. 

,r0  —  x^  =  amount  of  substance  retained  by  the  ether. 

k  —  division-coefficient. 

/  =  amount  of  water. 

m  =  amount  of  ether. 

<J£          _         Y 

—  -  I  =  concentration  of  the  ethereal  solution. 
m 


x 

—  L    =  concentration  of  the  aqueous  solution.  - 

Then  by  the  definition 


k  =  -]    ~  *»  ~  -*1  or  x,  = 


-    ~  , 

I  m  m 

kl 


m 

and  xn  —  x.  = 


0  m  H-  kl  * 

An  examination  of  the  last  expression,  which  gives  the  amount 
of  substance  removed  by  a  single  extraction,  shows  that  if  k 
is  large,  that  is,  if  the  substance  is  very  soluble  in  water  in  pro- 
portion to  its  solubility  in  ether,  the  amount  extracted  increases 
rapidly  with  the  amount  of  ether  used,  but  that  several  extrac- 
tions must  be  required.  If  k  is  small,  however,  an  increase  of  m, 
or  the  amount  of  ether,  has  little  effect  on  the  value  of  the  frac- 
tion and  a  few  extractions  with  a  small  amount  of  ether  will 
suffice. 

In  extracting,  after  adding  the  ether,  the  stop-cock  of  the  fun- 
nel should  be  inserted  and  held  firmly  in  place  while  the  contents 
are  shaken  vigorously.  Only  when  there  is  danger  of  forming 
an  emulsion  which  will  separate  into  layers  with  difficulty,  should 
the  agitation  of  the  liquids  be  more  gentle.  After  shaking,  the 
funnel  should' be  inverted,  and  the  stop-cock  opened  for  a  mo- 


HYDROXY    AND    KKTONIC    ACIDS  169 

ment  to  relieve  any  pressure  due  to  vapor  of  ether.  The  funnel 
is  then  set  upright  and  allowed  to  stand  till  the  two  layers  sep- 
arate. In  case  separation  does  not  take  place  satisfactorily  it 
may  be  necessary  to  add  more  ether,  or  a  few  drops  of  alcohol. 
In  extreme  cases,  filtration  on  a  plate,  or  through  a  tube  contain- 
ing some  cotton,  may  be  necessary.  Occasionally  an  emulsion 
can  be  caused  to  clear  by  connecting  the  funnel  with  the  pump 
and  exhausting  till  the  ether  boils  for  a  short  time.  When 
separation  has  taken  place,  the  aqueous  solution  is  drawn  off 
into  a  flask.  It  is  usually  an  advantage  when  the  solution  has  been 
nearly  removed,  to  give  the  funnel  a  slight  rotary  motion  to  col- 
lect the  solution  at  the  bottom,  where  it  can  be  drawn  off.  The 
ether  is  then  poured  from-  the  top  of  the  funnel  into  a  flask  or 
distilling  bulb,  care  being  taken  not  to  pour  out  any  drops  of  the 
aqueous  solution  which  may  remain. 

The  end  of  the  extraction  may  be  determined  by  taking  a  little 
of  the  ethereal  solution  in  a  dry  test-tube,  and  evaporating  the 
ether  quickly  by  immersion  in  a  boiling  water-bath,  and  finally 
inverting  the  tube  to  allow  the  vapor  of  ether  to  fall  out. 

In  working  with  small  quantities,  extractions  may  sometimes 
be  made  with  advantage  in  a  test-tube  and  the  ethereal  solution 
drawn  off  with  a  small  pipette,  suction  being  applied  to  the 
latter  through  a  rubber  tube  long  enough  for  the  eye  to  be 
brought  into  a  position  to  see  the  liquid.  It  is  an  advantage 
to  draw  the  pipette  out  to  a  capillary  below.  (See  Fig.  23,  p.  54.) 

The  ethereal  solution  of  the  mandelic  acid  should  be  distilled 
and  the  residue  dried  on  the  water-bath  in  a  watch-glass  or  por- 
celain dish.  The  acid,  which  crystallizes  on  cooling,  may  be  re- 
crystallized  from  benzene.  Yield  10  to  15  grams. 

Mandelic  acid  crystallizes  from  water  in  large  rhombic  crys- 
tals, and  from  benzene  in  leaflets,  which  melt  at  118°.  TOO 
parts  of  water  at  20°  dissolve  15.97  Parts  of  the  acid. 

As  with  all  substances  prepared  by  synthesis  from  inactive 
bodies  it  is  inactive,  but,  as  it  contains  an  asymmetric  carbon 
atom,  it  may  be  separated  into  two  active  forms.  The  separa- 
tion may  be  effected  by  the  crystallization  of  the  cinchonine  salt. 


I7O  ORGANIC    CHEMISTRY 

or  by  the  growth  of  Penicilium  Glaucum,  or  Sac  char  omyces 
ellipso'ideus  in  a  solution  of  the  ammonium  salt.  .The  former 
destroys  the  levo  form,  the  latter  the  dextro  form. 

75.  Preparation  of  an  Ester  by  Condensation  by  Sodium  Ethyl- 
ate.— Acetoacetic  ester,  CH3COCH2CO2C2H3.  (3-Butanonic  ethyl 
ester.) 

Literature — Geuther :  Jsb.  d.  chem.,  1863,  323;  1865,  302;  Frankland, 
Duppa:  Ann.,  135,  220;  138,  204;  Wislicenus,  Conrad:  Ibid,  186,  214: 
Michael:  J..  prakt.  Chem.  (N.  F.),  37,  473;  Nef :  Ann.,  266,  62;  270, 
331;  Freer:  Am.  Chem.  J.,  13,  310. 

20  grams   sodium. 
200  grams  acetic  ester. 

60  cc.  glacial  acetic  acid. 

60  cc.  water. 

100  cc.  salt  solution. 

The  acetic  ester  used  for  this  preparation  must  be  quite  pure, 
as  otherwise  its  action  on  sodium  will  be  too  violent.  If  a 
commercial  ester  of  good  quality  is  used,  it  will  suffice  to  allow  it 
to  stand  over  night  with  one-fifth  of  its  volume  of  granulated 
calcium  chloride,  and  filter  it  through  a  dry  filter.  If,  however, 
the  ester  is  less  pure  or  has  an  acid  reaction,  it  must  be  shaken 
with  a  strong  solution  of  sodium  carbonate  to  remove  acetic 
acid,  with  a  50  per  cent,  solution  of  calcium  chloride  to  remove 
alcohol,  dried  with  calcium  chloride,  distilled,  and  dried  again  as 
directed  above. 

Place  in  a  750  cc.  flask  20  grams  of  sodium  in  the  form  of 
wire,1  or  cut  in  thin  slices.  Connect  with  a  large  upright 
condenser,  and  pour  through  the  latter  200  grams  of  acetic  ester. 
The  heat  of  the  reaction  should  cause  the  ester  to  boil,  but  the 
reaction  should  not  be  violent.  When  the  action  appears  to 
slacken,  or  if  it  does  not  commence  after  a  short  time,  place  the 

1  For  this  and  similar  reactions  the  sodium  is  best  pressed  into  the  form  of  wire  by 
means  of  a  sodium  press.  The  surface  of  the  sodium  mnst  be  cut  clean,  and  it  must  not 
stand  in  the  air  before  it  is  put  into  the  press.  After  use,  the  press  should  be  cleaned 
with  alcohol  and  dried  immediatelv.  Finely  divided  sodium  may  also  be  easily  prepared 
by  putting  the  sodium  in  a  small  flask  with  some  xylene  and  heating  till  the  sodium 
melts.  The  flask  is  then  stoppered  and  shaken  vigorously  for  a  short  time.  When  cold 
the  xylene  may  be  decanted  and,  if  necessary,  the  globules  of  sodium  rinsed  by  decanta- 
tion  with  dry  ether  or  with  low  boiling  petroleum  ether. 


HYDROXY    AND    KETONIC    ACIDS 


171 


flask  on  a  water-bath  and  heat  gently  till  the  sodium  has  all  dis- 
solved. This  will  take  one  to  five  hours.  To  the  slightly  cooled 
solution  add,  with  vigorous  shaking,  60  cc.  of  glacial  acetic  acid 
diluted  with  an  equal  volume  of  water.  The  solution  should 
now  react  faintly  acid.  Add  100  cc.  of  a  cold  saturated  solution 
of  common  salt,  shake,  add  enough  water  to  dissolve  any  salt  that 
separates,  separate  the  upper  layer  containing  the  acetoacetic  ester 
by  means  of  a  separatory  funnel,  and  distil  from  a  500  c.  distill- 
ing bulb,  best  of  Ladenburg's  form  (Fig.  36),  till  the  thermom- 
eter reaches  95°.  This  portion  of  the  distillate  contains  acetic 
ester,  and  may  be  purified  and  used  again.  Transfer  the  resi- 


Fig.  34- 

due  in  the  distilling  bulb  at  once  to  a  100  cc.  distilling  bulb  fitted 
with  a  capillary  tube,  thermometer,  and  a  second  bulb  connected 
to  the  side  tube  to  collect  the  distillate  (Fig.  34).  Heat  in  an 
oil-bath1  or  in  an  air-bath  consisting  of  a  wrought  iron  cruci- 
ble, so  placed  that  the  bulb  does  not  touch  it"  at  any  point.  Distil 
under  a  pressure  of  30-40  mm.  till  the  thermometer  reaches  80°, 
or  to  90°  under  a  pressure  of  100  mm.  Change  the  bulb  used 
as  a  receiver  and  continue  the  distillation,  cooling  the  receiver 
by  running  water  over  it.  If  the  pressure  remains  constant, 

1  A  bath  of  Wood's  metal  is  especially  convenient,  if  this  is  available.  The  first  cost 
is  considerably  greater  than  that  of  oil  but  it  is  much  cleaner  and  may  be  used  almost  in- 
definitely. For  an  oil-bath  cotton-seed  oil  is  suitable  or  a  mineral  oil  with  a  very  high 
flashing  point. 


172 


ORGANIC    CHEMISTRY 


after  the  boiling-point  of  the  acetoacetic  ester  is  reached,  it  will 
all  pass  over  within  an  interval  of  a  few  degrees.  The  ester 
obtained  by  the  first  distillation  should  be  fractioned  once  or 
twice  under  diminished  pressure,  and  the  ester  finally  obtained 
should  boil  within  an  interval  of  2°  to  3°,  if  the  pressure  is 
constant.  Yield  45  to  50  grams. 

The  ester  may  also  be  distilled  under  ordinary  pressure,  but  the 
yield  is  much  less. 

The  success  of  this  preparation  depends  very  greatly  on  rapid 
work.  If  sodium  in  the  form  of  wire  is  used,  the  whole  prepara- 


Fig.  35-  Fig.  36. 

tion  should  be  completed  in  three  or  four  hours.  If  the  prepara- 
tion is  interrupted  at  any  point,  and  especially  if  allowed  to  stand 
over  night,  the  yield  is  greatly  diminished. 

For  the  second  distillation  under  diminished  pressure  a 
Claisen  distilling  bulb  (Fig.  35)  can  be  used  with  advantage.  In 
all  such  distillations  the  temperature  of  the  oil,  metal-  or  air-bath 
should  rise  very  slowly,  and  an  oil-batn  should  not  be  heated 
much  hotter  than  the  boiling-point  of  the  substance  distilled. 
The  capillary  tube  is  to  start  bubbles  of  vapor  and  prevent  bump- 
ing. It  is  best  made  from  a  capillary  tube  5-6  mm.  outside 
diameter,  and  drawn  out  to  a  fine  thread. 

Many  different  forms  of  apparatus  have  been  devised  for 
distillation  under  diminished  pressure  (Bruhl:  Ber.,  21,  3339; 


HYDROXY    AND    KETONIC    ACIDS 


173 


Lothar  Meyer :  Ibid,  20,  1833 ;  Fuchs :  Z.  anal.  Chem.,  29,  591 ; 
Mabery:  Am.  Chem.  J.,  17,  722),  but  for  most  cases  which  arise 
in  ordinary  practice,  the  simple  apparatus  of  Fig.  34>  if  a  stream 
of  cold  water  is  kept  running  over  the  receiving  bulb,  answers 
every  purpose.  A  good  "Bunsen"  pump  which  will  reduce  the 
pressure  quickly  to  30  mm.  or  less,  when  the  water  is  cold,  is, 
of  course,  required.  The  author  has  found  that  of  E.  C.  Chap- 
man, large  size,  the  most  satisfactory. 

For  substances  of  very  high  boiling-point  or  which  decompose 
easily  a  mechanical  pump  (Geryk's)  which  will  reduce  the  pres- 


7*0 

700 

-600 


-300 

200 
•  /SO 
•IOO 

-  SO 


Fig.  37-  A 

sure  to  i  mm.  or  less  is  of  very  great  advantage,  as  a  further  de- 
crease in  boiling-point  of  about  100°  may  be  obtained  in  this  way. 
It  is  very  convenient  to  have  a  manometer  attached  in  such  a 
manner  that  the  pressure  can  always  be  known  whenever  the 
pump  is  used.  That  shown  in  Fig.  37  has  been  in  use  in  the 
author's  laboratory  for  some  years,  and  has  the  advantage  over 
the  usual  forms  that  the  whole  scale,  from  no  pressure  to  that 
of  the  atmosphere,  occupies  a  space  of  only  about  18-20  cm., 
and  further  that  the  air  in  the  closed  end  above  the  mercury 


174  ORGANIC    CHEMISTRY 

acts  as  a  cushion  and  there  is  no  danger  of  breakage  when  the 
pressure  is  suddenly  released.  It  is  an  advantage  to  have  a 
portion  of  the  bend  at  A,  of  capillary  tubing  I  mm.  or  less  in 
diameter. 

The  manometer  is  calibrated  after  it  is  put  in  position  by  com- 
parison with  the  manometer  of  the  usual  form  for  low  pressures, 
both  being  connected  with  the  same  receptacle,  which  is  exhausted 
by  the  pump.  For  higher  pressures  it  is  calibrated  by  connecting 
with  a  small  tube  standing  perpendicularly  in  a  dish  of  mercury, 
subtracting  the  height  of  mercury  in  the  tube  from  the  height  of 
the  barometer  for  the  day. 

Acetoacetic  ester  is  a  colorless  liquid  with  an  unpleasant  odor. 
It  boils  at  181°,  and  has  a  specific  gravity  of  1.030  at  15°. 
Under  diminished  pressure  it  boils : 

Under  12.5  mm.  at  71*. 

18.0     "  "  79°. 

"       29.0     "  "  88°. 

"      59-0     "  "  97°. 

"       80.0     "  "  100°. 

It  is  slightly  soluble  in  water  and  is  volatile  with  water  vapor. 
It  gives  a 'crystalline  compound  with  sodium  bisulphite,  which 
may  be  used  as  a  means  of  purification.  It  gives  with  ferric 
chloride,  in  aqueous  solutions,  a  violet  color — characteristic  of 
ortho  hydroxy  derivatives  of  benzoic  acid,  and  of  other  com- 
pounds of  similar  structure.  It  is  soluble  in  cold  dilute  alkalies 
without  decomposition,  but  on  warming  with  alcoholic  potash 
it  is  decomposed,  chiefly  with  formation  of  two  molecules  of 
acetic  acid  and  alcohol  (acid  decomposition).  Boiling  it  with 
dilute  acids  or  alkalies  decomposes  it  mainly  with  the  formation 
of  acetone,  carbon  dioxide,  and  alcohol  (ketonic  decomposition). 
For  the  use  of  acetoacetic  ester  in  syntheses,  see  p.  in. 

On  heating  by  itself,  it  decomposes  with  the  formation  of 
dehydracetic  acid,  C8H8O4.  This  can  be  recovered  from  the 
residues  after  distilling  off  the  acetoacetic  ester,  by  boiling  them 
with  sodium  carbonate  and  bone-black  and  crystallizing  the  so- 
dium salt,  after  filtration.  The  latter  is  then  decomposed  with 


HYDROXY    AND    KETONIC    ACIDS  IJ5 

dilute    sulphuric   acid.     The    acid    crystallizes   in   needles    which 
melt  at  109°.      (Feist:  Ann.,  257,  253.) 

By  condensation  of  acetoacetic  ester  with  aldehyde  ammonia, 
a  pyridine  derivative  is  formed,  with  aniline  a  chinoline  deriva- 
tive, with  phenyl  hydrazine  a  pyrazolone  compound,  and  with 
amidines  pyrimidine  compounds. 

76.  Condensation  of   Acetoacetic   Ester   with   Itself. — Diacetyl 

CH3CO  —  CH  -  C02C2H5 
succinic  ester, 

CH3CO  —  CH  —  CO2C2H5 

Literature — Rugheimer :  Ber.,  7,  892;  Harrow:  Ann.,  201,  144;  Nef : 
Ibid,  266,  88;  Knorr:  Ber.,  22,  170,  2100;  Paal :  Ibid,  18,  58,  2251. 

150  cc.  dry  ether. 

4  grams   sodium. 

20  grams  acetoacetic  ester. 

20  grams  iodine. 

100  cc.  ether. 

Prepare  some  pure,  dry  ether  as  follows  r1  Fill  a  half  liter 
Ladenburg  distilling  bulb  (see  75,  p.  172)  one-fourth  full  with 
granular  calcium  chloride.  Place  in  the  bulb  an  inverted  test- 
tube  of  such  size  and  length  as  to  reach  just  to  the  bottom  of 
the  neck  and  nearly  close  it,  when  resting  on  the  bottom  of  the 
bulb.  Fill  the  neck  nearly  to  the  side  tube  with  granular  calcium 
chloride,  and  then  fill  the  bulb  nearly  to  the  neck  with  ordinary 
ether.  Stopper  the  bulb  and  allow  it  to  stand  over  night.  Then 
distil  on  a  water-bath,  using  a  thermometer,  and  collecting  the 
ether  in  a  dry  bottle.  Change  the  receiver  as  soon  as  the  ther- 
mometer rises  0.2°  above  the  boiling-point  of  pure  ether.  The 
ether  dried  in  this  way  will  answer  for  this  preparation.  For 
a  perfectly  anhydrous  ether  some  sodium  wire  must  be  pressed 
into  it,  and  the  ether  distilled  after  standing  for  a  day.  See, 
however,  pp.  82  and  74. 

Ether  should  be  kept  in  bottles  with  a  smooth  neck,  and  closed 
with  a  tightly  fitting  cork,  not  with  a  glass  or  rubber  stopf  er. 
The  stock  of  ether  should  be  kept,  as  far  as  possible,  in  bottles 

;  Method  suggested  by  Dr.  H.  H.  Ballard. 


176  ORGANIC    CHEMISTRY 

which  are  filled  full,  as  the  loss  is  chiefly  due  to  the  expansion 
and  contraction  of  the  air  above  the  ether,  which  always  carries 
with  it  some  of  the  vapor.  The  same  is  true  of  other  volatile 
liquids. 

Place  in  a  300  cc.  flask  about  150  cc.  of  dry  ether,  weigh 
carefully,  and  press  into  the  flask  about  four  grams  of  sodium 
wire,  taking  care,  of  course,  that  there  is  no  appreciable  loss 
of  ether  by  evaporation.  Weigh  again,  connect  with  an  upright 
condenser,  and  for  each  gram  of  sodium  add  five  grams  of 
acetoacetic  ester.  Shake  occasionally  till  the  sodium  is  all  dis- 
solved, which  will  take  from  one  to  two  hours.  When  an  evo- 
lution of  hydrogen  is  no  longer  observed,  after  shaking,  add  in 
small  portions  with  shaking,  a  solution  of  about  20  grams  of 
finely  powdered  iodine  in  dry  ether.  Continue  the  addition  only 
so  long  as  the  color  of  the  iodine  disappears  immediately  after 
each  addition.  Filter  from  the  sodium  iodide,  distil  the  ether, 
and  crystallize  the  residue  of  diacetylsuccinic  ester  from  glacial 
acetic  acid. 

Diacetylsuccinic  ester  crystallizes  in  needles,  or  in  monoclinic 
plates,  which  melt  at  88°. 

If  saponified  by  strong  caustic  soda  at  ordinary  temperatures, 
the  free  acid  can  be  obtained.  If  saponified  by  a  3  per  cent, 
solution  of  caustic  soda,  in  exactly  equivalent  amounts,  however, 
acetonylacetone,  alcohol,  and  carbon  dioxide  are  formed. 

77.  Synthesis  of  an  Acid  by  Condensation  of  Acetoacetic  Ester 
with  a  Halogen  Compound. — Hydrocinnamic  acid, 

C6H5CH12CH2C02H, 
( Phen-3-propanoic  acid )  .* 

Literature. — Alexejew,  Erlenmeyer:  Ann.,  121,  375;  137,  327;  Gabriel, 
Zimmermann :  Ber.,  i3»  1680;  Fittig,  Kiesow :  Ann.,  156,  249;  Sesemann  : 
Ber.,  6,  1086;  10,  758;  Conrad,  Hodgkinson :  Ann.,  193*  300;  Conrad:  Ibid, 
204,  136;  Conrad,  Bischoff:  Ibid,  204,  180;  Fittig,  Christ:  Ibid,  268,  122; 
For  benzyl  acetone,  Ehrlich :  Ibid,  187,  n  ;  Jackson:  Ber.,  14,  890;  Harries, 
Esch«nbach:  Ibid,  29,  383. 

1  This  acid  is  called,  in  the  Third  Edition  of  Beilstein,  phenathylsaure,  but  that  name 
does  not  agree  with  the  principles  of  nomenclature  proposed  by  the  Geneva  Congress 
and  Beilstein  uses  the  same  name  elsewhere  for  a-toluic  acid, 


HYDROXY     AND   ^KETONIC    ACIDS  I7/ 

2.3  grams  sodium. 

35  cc.  absolute  alcohol. 

13   grams   acetoacetic   ester. 
12.6  grams  benzyl  chloride. 

15  grams    (about)   benzyl  acetoacetic  ester. 

30  cc.  alcohol. 

10  grams  sodium  hydroxide. 

30  cc.   water. 

40  cc.  hydrochloric  acid   (sp.  gr.   i.n). 

Put  2.3  grams  (i  mol.)  of  sodium  in  a  100  cc.  flask.  Add 
35  cc.  of  absolute  alcohol,  connect  with  an  upright  condenser, 
and  heat  on  a  water-bath  till  the  sodium  is  dissolved.  Cool,  add 
13  grams  (i  mol.)  of  acetoacetic  ester,  which  on  shaking  will 
cause  the  sodium  ethylate,  which  has  separated,  to  dissolve.  Add 
12.6  grams  (i  mol.)  of  benzyl  chloride,  and  heat  on  the  water- 
bath  with  an  upright  condenser  for  two  hours.  The  solution 
should  now  react  neutral  when  a  piece  of  dry  reddened  litmus 
paper  -is  dipped  in  it  and  afterwards  moistened.  Cool,  fitter 
on  a  dry  filter  with  the  pump,  and  wash  twice  with  a  little  al- 
cohol. Distil  the  solution  under  ordinary  pressure  till  the  ther- 
mometer reaches  110°,  and  then  under  diminished  pressure,  lin- 
ing an  oil-  or  metal-bath.  The  Claisen  distilling  bulb  may  be  used 
with  advantage  (see  75,  p.  172).  The  portion  boiling  at  160°- 
170°  under  a  pressure  of  12  mm.,  or  i8o°-i9O°  under  a  pressure 
of  TOO  mm.,  will  be  nearly  pure  benzyl  acetoacetic  ester. 

/COCH, 
C6H.  —  CH2—  CH< 

XCO,C2H5 

A  small  portion,  which  boils  at  70°  higher,  consists  of  dibenzyl 
acetoacetic  ester;  12-15  grams  of  the  monobenzyl  acetoacetic 
ester  should  be  obtained. 

Put  the  benzyl  acetoacetic  ester  in  a  200  cc.  flask,  add  30  cc. 
of  alcohol,  and  10  grams  of  sodium  hydroxide  dissolved  in  30  cc. 
of  water.  Boil  with  an  upright  condenser  for  an  hour.  Cool, 
dilute  with  about  50  cc.  of  water,  and  extract  twice  with  10-20 


178  ORGANIC    CHEMISTRY 

cc.  of  ether.  Distil  off  the  ether,  dry  the  ketone  which  remains 
in  vacua  over  sulphuric  acid,  and  distil  ;  or  the  ethereal  solution 
may  be  dried  with  ignited  potassium  carbonate  before  the  ether 
is  distilled  away. 

Evaporate  the  alkaline  solution  to  about  20  cc.  and  add  40  cc. 
of  hydrochloric  acid  (sp.  gr.  i.n).  The  hydrocinnamic  acid 
usually  separates  as  an  oil,  at  first,  but  will  solidify  on  stand- 
ing in  a  cool  place  for  some  time.  Filter,  and  recrystallize  from 
hot  water,  reserving  a  very  small  crystal  to  cause  the  solidifica- 
tion of  the  acid,  in  case  it  separates  again  as  an  oil. 

The  yield  of  the  ketone  and  of  the  acid  is  about  3  grams  each, 
but  better  yields  may  be  obtained  by  working  with  larger  quan- 
tities. 

Benzyl  acetone  (i,  3-butylonephen  C6H5CH,2CH2COCH3)  is  a 
liquid  which  boils  at  235°-236°,  and  has  a  specific  gravity  of 

0.989  at  . 


Hydrocinnamic  acid  crystallizes  in  long  colorless  needles,  which 
melt  at  49°.  It  boils  at  280°.  It  is  easily  soluble  in  boiling 
water,  and  in  alcohol  and  ether.  It  is  volatile  in  water  vapor. 
It  dissolves  in  168  parts  of  water  at  20°. 

78.  Preparation     of     a     Pyrazolone     Derivative  .—  Antipyrine, 


CO       N  —  CH3     i-Phenyl-2,3-dimethyl-pyrazolone. 

I  I 

CH  =  C—  CH3 

Literature  —  Knorr:  Ber.,  16,  2597;  17,  549,  2037;  28,  706;  Ann.,  238, 
137;  279,  188;  293,  i;  Marckwald:  Ibid,  286,  350;  Nef  :  Ibid,  266,  131; 
287»  353;  Bender:  Ber.,  20,  2747;  Patents,  Knorr:  Ibid,  *7>  R,  149: 
Meister,  Lucius,  and  Briining:  Ibid,  18,  R,  725;  20,  R,  609;  27,  R,  282, 

13  grams  acetoacetic  ester. 
10  grams  phenyl  hydrazine. 

10  grams   i-phenyl-3-methylpyrazolone. 
10  grams  methyl  iodide. 
10  grams  methyl  alcohol. 


HYDROXY    AND  ^KETONIC    ACIDS  1/9 

Put  in  a  flask  13  grams  of  acetoacetic  ester,  add  10  grams  of 
phenyl  hydrazine,  and  heat  on  the  water-bath  for  two  hours,  or 
till  a  drop  of  the  mixture  becomes  perfectly  solid  on  treating  with 
a  little  ether  on  a  watch-glass.  Pour  the  warm  mass,  with  stir- 
ring, into  a  small  amount  of  ether,  filter,  wash  with  ether,  and 
dry. 

The  acetoacetic  ester  and  phenyl  hydrazine  condense  at  first 
with  the  formation  of  a  hydrazide, 

c\ 

C  —  NH  -  NH—  C6H5, 

I! 

C2H5—  C02CH 
and  this,  on  heating,  condenses,  with  loss  of  alcohol,  to  i  -phenyl. 


N 

s\ 

3-methylpyrazolone,       CO      NH.        In    working    with    larger 

I  I 

HC    --=  C  —  CH3 

amounts  it  may  be  desirable  to  separate  the  water  formed  by  the 
first  condensation  as  Knorr  suggests,  but  the  directions  given 
are  satisfactory  for  small  amounts.  The  phenylmethylpyrazolone 
melts  at  127°,  is  almost  insoluble  in  cold  water,  ether  and  ligrom, 
more  easily  soluble  in  hot  water,  and  very  easily  soluble  in 
alcohol.  It  dissolves  both  in  acids  and  alkalies. 

Put  in  a  thick  walled  tube  10  grams  of  the  phenylpyrazolone, 
10  grams  of  methyl  iodide,  and  10  grams  of  methyl  alcohol.  Seal 
carefully,  (see  p.  156),  and  heat  in  a  bomb  oven,  or  in  an  iron 
tube  (to  guard  against  explosion)  in  a  water-bath  for  two  to 
three  hours.  Cool,  open  the  capillary  by  softening  in  a  flame,  cut 
off  the  end,  transfer  the  contents  of  the  tube  to  a  beaker,  add  a 
small  amount  of  a  solution  of  sulphur  dioxide,  and  some  water, 
boil  to  expel  the  alcohol,  cool,  add  sodium  hydroxide  in  slight 
excess,  and  extract  several  times  with  a  small  amount  of  chloro- 
form. Distil  off  the  chloroform,  and  crystallize  the  antipyrine 


ISO  ORGANIC    CHEMISTRY 

from   toluene.     The   yields   are   nearly   quantitative,   except    for 
the  loss  in  manipulations. 

Antipyrine  crystallizes  in  leaflets,  which  melt  at  116°.  It  is 
easily  soluble  in  water,  alcohol,  benzene,  and  chloroform,  diffi- 
cultly soluble  in  ether  and  ligroin.  The  aqueous  solution  is 
colored  red  by  ferric  chloride.  Dilute  solutions  give  a  bluish 
green  color  with  nitrous  acid. 

79.  Succinylosuccinic  Ester. — 
C2H6— O— CO— C  =  C(OH;  —  CH, 

CH2— C(OH)  ==  C— CO— O— C2H5. 

Literature — Fehling:  Ann.,  49,  186;  Herrmann:  Ibid,  211,  306;  Duis- 
berg:  Ber.,  16,  133;  Wedel :  Ann.,  219,  94;  Baeyer:  Ber.,  19,  432;  Mewes : 
Ann.,  245,  74;  Baeyer  u.  Noyes :  Ber.,  22,  2168;  Pinner:  Ibid,  22,  2623; 
Piutti:  Gas.  chim.  ital.,  22,  167. 

50  grams  succinic  ester. 

13.5  grams  sodium. 

2  cc.  absolute  alcohol. 

Place  in  a  100  cc.  round-bottomed  flask  50  grams  of  succinic 
ester  (see  p.  152)  and  2  cc.  of  absolute  alcohol.  Press  into  the 
flask  13.5  grams  of  sodium  in  the  form  of  wire.  (In  such 
cases  it  is  desirable  to  know  how  much  sodium  will  be  left  in 
the  press  when  the  piston  is  forced  to  the  bottom  and  allowance 
should  be  made  for  this.  The  press  must  be  cleaned  with  alcohol 
and  dried  immediately  after  use.  Instead  of  sodium  wire  finely 
divided  sodium  prepared  as  directed  on  p.  170  may  be  used.) 
During  the  addition  of  the  sodium  have  a  dish  of  cold  water  at 
hand,  and  cool  the  flask  by  immersion  in  this,  if  the  reaction 
becomes  violent.  The  flask  should  always  be  allowed  to  grow 
warm,  but  should  not  become  so  hot  as  to  melt  the  sodium. 
When  the  sodium  has  all  been  added,  and  the  reaction  has  pro- 
gressed far  enough  so  that  the  mixture  no  longer  tends  to  grow 
hot,  connect  the  flask  with  an  upright  condenser  and  heat  on  a 
water-bath  for  two  hours.  Stopper  the  flask  and  allow  it  to  cool. 
The  mixture  can  be  left  at  this  po'nt  over  night  without  harm, 
perhaps  with  advantage.  The  yield  can  be  increased  by  longer 
heating  or  longer  standing,  but  the  time  taken  is  usually  worth 


HYDROXY    AND    KETONIC    ACIDS  l8l 

more  than  the  material  saved.  The  contents  of  the  flask -should, 
at  the  end  of  the  time,  be  converted  into  a  dry,  solid  mass. 

Put  into  a  500  cc.  beaker  200  cc.  of  water  and  150  cc.  of  dilute 
sulphuric  acid  (25  per  cent.,  sp.  gr.  1.18).  Set  the  beaker 
in  a  large  dish  of  cold  water,  and  conduct  to  the  surface  of  the 
acid  a  slow  current  of  carbon  dioxide,  which  will  prevent  the 
particles  of  unchanged  sodium  from  taking  fire  as  they  dissolve 
in  the  acid.  Add  the  material  from  the  flask  to  the  acid  in  small 
portions  with  vigorous  stirring.  It  is  frequently  necessary  to 
break  the  flask  to  get  the  sodium  salt,  but  the  latter  should  not  be 
exposed  to  the  air  long  before  it  is  thrown  into  the  acid. 

The  crude  succinylosuccinic  ester  which  separates  is  filtered  off 
on  a  plate,  and  washed  with  cold  water.  The  crude  ester,  after 
sucking  as  dry  as  possible,  is  then  crystallized  from  hot  alcohol. 
For  this  purpose  put  in  a  500  cc.  flask  about  300  cc.  of  alcohol 
and  add  the  ester  only  in  such  quantity  that  it  dissolves  quite 
readily  on  boiling  the  alcohol  on  a  water-bath.  Filter  hot  and 
very  quickly  on  a  plate,  transfer  the  filtrate  to  a  clean  flask  and 
cool  rapidly  under  the  tap  till  the  ester  has  crystallized.  Filter 
on  another  plate  with  a  clean  filter.  Transfer  the  filtrate  to  the 
first  flask,  add  more  of  the  ester,  boil,  filter,  crystallize  and  collect 
the  crystals  on  top  of  the  first  lot.  Repeat  till  all  of  the  ester 
has  been  crystallized,  then  wash  the  crystals  once  with  pure  alco- 
hol and  repeatedly  with  dilute  alcohol. 

Succinylosuccinic  ester  forms  yellowish  or  greenish  crystals 
which  melt  at  127°.  It  is  almost  insoluble  in  cold  water,  slightly 
soluble  in  hot  water,  and  difficultly  soluble  in  cold  alcohol.  The 
pure  alcoholic  solution  has  a  beautiful  blue  fluorescence,  and  is 
colored  onion-red  by  ferric  chloride.  The  ester  dissolves  in  dilute 
caustic  soda,  and  is  saponified  with  formation  of  the  products  of 
both  acid  and  ketonic  decomposition  by  allowing  the  solution  to 
stand  (Herrmann:  Ann.,  211,  322).  A  clean  ketonic  decom- 
position with  the  formation  of  diketohexamethylene  (cyclohex- 
anedione  1.4)  can  be  obtained  by  boiling  with  dilute  sulphuric 
acid.  (Baeyer:  Ann.,  278,  91.) 

By  suspending  in  carbon  disulphide  and  treating  with  the  cal- 


1 82  ORGANIC    CHEMISTRY 

culated'  amount  of  bromine,   it  is   converted  quantitatively  into 
dihydroxyterephthalic  ester. 

80.  Preparation  of  Ethyl  Dihydroxymalonate  and  Ethyl  Oxo- 
malonate. —  (Ethyl  ester  of  mesoxalic  acid), 

H  —  O         C02C2H5  C02C2H6 

C  and  CO 

/\  \ 

H  —  O         CO2C2H5  CO2C2H5 

Literature — Curtiss:  Am.  Chem.  J.,  35,  477;  Curtiss  and  Spencer:  J. 
Am.  Chem.  Soc.,  31,  1054;  Conrad,  Bruckner:  Ber.,  24,  3000;  Anschiitz, 
Parlato :  Ber.,  25,  3615 ;  Color  of  organic  compounds,  Curtiss :  J.  Am. 
Chem.  Soc.,  32,  795. 

35  grams  malonic  ester. 

35  grams  oxides  of  nitrogen  (NO  and  NO2). 

Put  35  grams  of  malonic  ester  (see  p.  136)  in  a  100  cc.  flask 
and  cool  it  to  — 13°  with  ice  and  salt  or  ice  and  commer- 
cial hydrochloric  acid.  Pass  into  the  weighed  flask  the  oxides 
of  nitrogen  prepared  by  dropping  nitric  acid  (sp.  gr.  1.42) 
slowly  upon  100  grams  of  arsenic  trioxide  while  the  mixture  is 
gently  warmed.  Pass  the  'gases  .through  an  empty  flask  or 
wash  bottle  to  condense  moisture.  Continue  the  passage  of  the 
gas  till  the  flask  gains  35  grams  in  weight.  Pack  the  flask  in  the 
freezing  mixture  and  allow  it  to  stand  over  night,  closing  it  with 
a  cork  stopper  bearing  a  tube  closed  with  a  Bunsen  valve.1  Then 
allow  the  ice  to  melt  and  the  mixture  to  come  to  room  tempera- 
ture, allowing  it  to  stand  for  24  hours  longer.  Note  the  loss  in 
weight.  The  color  should  now  be  dark  green.  Aspirate  or  blow 
air  through  the  liquid  for  10-15  minutes  to  remove  the  excess 
of  oxides  of  nitrogen.  Distil  the  residue  under  diminished  pres- 
sure, using  a  Raikoff  receiver,  (Chem.  Ztg.,  1888,  693),  col- 
lecting the  distillate  in  three  portions,  the  first  containing  water, 
acetic  acid  and  ester,  the  second,  colorless  dihydroxy  malonic 
ester  and  the  third,  to  be  collected  when  the  distillate  becomes 

green,  oxomalonic  ester, 

1  A  piece  of  soft  rubber  tubing  closed  at  the  end  with  a  glass  rod  and  having  two 
short,  longitudinal  slits  cut  in  its  walls. 


KYDROXY    AND   ATONIC    ACIDS  183 

To  obtain  the  dihydroxymalonic  ester  from  the  green  oxo- 
malonic  ester  allow  it  to  stand  in  the  air  for  some  hours  with 
occasional  stirring.  Water  will  be  absorbed  and  the  substance 
will  pass  over  into  the  colorless,  crystalline  hydroxy  compound. 
When  the  transformation  appears  to  be  complete  filter  on  a  plate 
(p.  120)  and  suck  as  dry  as  possible.  Stop  the  pump,  moisten 
the  crystals  with  a  little  carbon  disulphide  and  suck  off  again. 
Repeat  twice  and  then  recrystallize  from  a  mixture  of  equal 
parts  of  ligro'in  and  benzene.  Dihydroxymalonic  ester  crystal- 
lizes in  colorless  plates  which  melt  at  57°.  Yield  28  to  30 
grams. 

The  anhydrous  keto  ester  may  be  prepared  by  mixing  the  di- 
hydroxy  compound  with  twice  its  weight  of  phosphorus  pent- 
oxide  (about  3  mols.)  in  a  large  distilling  bulb  and  distilling 
under  diminished  pressure  after  standing  for  twenty-four  hours. 
It  boils  at  115°  under  a  pressure  of  29  mm. 

Dihydroxymalonic  ester  furnishes  an  illustration  of  the  fact 
that  when  a  carbon  atom  is  combined  with  one  or  two  negative 
groups  it  may  retain  two  hydroxyl  groups  in  combination.1  To 
show  the  dissociation  of  the  compound  put  0.25  gram  in  a  test- 
tube  and  warm  very  gently  till  it  melts.  Xotice  that  the  liquid  is 
colorless.  Raise  the  temperature  to  9O°-ioo°.  As  the  com- 
pound dissociates  and  the  water  distils  to  the  upper  part  of  the 
tube  the  thick  oil  which  remains  gradually  becomes  greenish  in 
color,  the  three  carbonyl  groups  acting  as  a  chromophore  group. 
The  saturation  of  the  central  carbonyl  group  by  the  addition  of 
water,  hydrochloric  acid  or  other  compounds  destroys  the  chromo- 
phore grouping.  Cork  the  tube  and  allow  it  to  stand  and  notice 
the  gradual  recombination  of  the  oxomalonic  ester  and  water  to 
form  the  crystalline,  colorless  dihydroxy  compound. 

1  Another  illustration  is  chloral  hydrate.  In  crystallized  oxalic  acid  three  hydroxyl 
groups  are  probably  combined  with  a  single  carbon  atom. 


Chapter  X 

CARBOHYDRATES 

The  most  important  carbohydrates  are  sucrose,'  maltose,  lac- 
tose, glucose  and  fructose,  of  the  sugars,  and  dextrin,  starch 
and  cellulose  of  the  more  complex  compounds  of'  the  group. 

Sucrose  or  cane  sugar  is  prepared  from  the  juice  of  the  sugar 
cane,  the  sugar-beet  or  from  the  sap  of  the  maple.  It  crys- 
tallizes well  from  water  and  from  alcohol  and  is  easily  obtained 
in  a  high  dgree  of  purity.  Lactose,  or  milk-sugar  is  obtained 
from  the  whey  which  remains  after  separating  casein  from  milk 
in  the  manufacture  of  cheese.  Maltose  is  formed,  together  with 
dextrin,  by  the  action  of  the  enzyme,  diastase,  of.  malt,  on  starch. 
Glucose  is  prepared,  commercially,  by  the  hydrolysis  of  starch 
with  dilute  acids  and  crystallized  rf-glucose  is  now  an  article  of 
commerce.  In  the  laboratory  it  is  more  easily  obtained  from  the 
mixture  of  ^/-glucose  and  d'-fructose  obtained  by  the  hydrolysis 
of  sucrose.  (Soxhlet:  J.  prakt.  Chem.  [2],  21,  244;  Miiller:  Ibid. 
[2],  26,  83;  Otto:  Ibid,  [2],  26,  91.)  <f -Fructose  may  be  pre- 
pared from  the  same  mixture  by  first  combining  it  with  calcium 
to  form  a  difficulty  soluble  compound  (Dubrunfant:  Bull.  soc. 
chin*!.,  13,  350.  See  also  Girard :  Bull.  soc.  chim.,  33,  154). 

Starch  is  prepared,  chiefly  by  mechanical  processes,  from  corn 
or  maize,  potatoes,  wheat  or  rice,  the  first  two  being  the  chief 
commercial  sources.  It  cannot  be  crystallized  and  the  molecular 
weight  is  not  known. 

Dextrin  ;s  a  hydrolytic  product,  intermediate  between  starch 
and  maltose  or  (/-glucose,  formed  by  the  action  of  diastase  or  of 
acids  on  starch.  Several  different  forms,  which  are  fairly  dis- 
tinct in  their  properties,  have  been  prepared.  All  forms  are 
insoluble  in  alcohol  and  easily  soluble  in  water.  (See  Lintner 
and  Dull :  Rer.,  26,  2543.  and  Brown  and  Millar:  I.  Chem.  Soc., 
75,  288.) 

Cellulose   is   prepared    by   the    successive   treatment   of   cotton 


CARBOHYDRATES  185 

or  other  natural  fibers  with  ether,  alcohol,  water,  alkalies  and 
dilute  hydrochloric  and  hydrofluoric  acids  to  remove  all  sub- 
stance soluble  in  these  solvents.  Cross,  Bevan  and  Beadle  dis- 
tinguish three  forms.  (Ber.,  26,  2524;  J.  Chem.  Soc.,  67,  438.) 
Cellulose  is  dissolved  by  Schweitzer's  reagent  (p.  189),  but  is 
probably  changed,  chemically,  by  the  process  (Bumcke  and  Wolf- 
enstein:  Ber.,  32,  2494). 

The  most  important  quantitative  methods  for  the  determina- 
tion of  sugars  are  the  determination  of  the  specific  gravity  of 
solutions.,  the  determination  of  the  rotation  of  polarized  light 
with  the  polarimeter  or  saccharimeter  and  the  determination  of 
reducing  sugars  with  Fehling's  solution,  (see  below). 

The  most  important  reactions  which  have  established  the  struc- 
ture of  some  of  the  sugars  are  the  preparation  of  pentacetyl  glu- 
cose (Erwig  and  Konigs :  Ber.,  22,  1464),  the  preparation  of  the 
cyanhydrine  and  of  glucoheptonic  acid  (Kiliani:  Ber.,  19,  768; 
Fischer:  Ann.,  270,  71  and  84)  and  the  reduction  of  the  latter 
to  normal  heptylic  acid  (Kiliani:  Ber.,  19,  1130;  E.  Fischer, 
Tafel :  Ber.,  21,  2175),  the  preparation  of  glucosazone  from  both 
d-  glucose  and  (/'-fructose,  (p.  191)  and  the  relation  established 
between  the  molecular  rotation  of  the  a  and  (3  forms  of  the 
sugars  (Hudson:  J.  Am.  Ch.  Soc.,  31,  66). 

The  formation  of  furfural  from  pentoses  furnishes  an  im- 
portant method  for  the  quantitative  determination  of  pentosans 
(p.  190). 

The  formation  of  levulinic  acid  from  glucose  (p.  192)  and  of 
alcohol  from  glucose  or  fructose  are  illustrations  of  complex 
rearrangements  which  may  be  produced  in  carbohydrates  by  di- 
lute acids  or  enzymes. 

81.  Fehling's  Solution.  Its  Effect  on  Some  of  the  Sugars.  In- 
version of  Sucrose. 

Literature — History  of  Fehling's  solution,  Herstein :  J.  Am.  Ch.  Soc., 
32i  779;  Use  for  the  quantitative  determination  of  rf-glucose  and  of  in- 
vert sugar,  alone  and  in  the  presence  of  sucrose,  Munson  and  Walker : 
J.  Am.  Ch.  Soc.,  28,  663 ;  Quantitative  determination  of  lactose  and  mal- 
tose, Walker :  J.  Am.  Ch.  Soc.,  29,  541 ;  Chemical  action  of  Fehling's 
solution,  Nef :  Ann.,  357,  214 :  Theory  of  the  failure  of  copper  to  pre- 


1 86  ORGANIC    CHEMISTRY 

cipitate  in  an  alkaline  solution,  Meyer  and  Jacobson :  Lehrb.  Org.  Chem., 
i  Aufl.,  Vol.  i,  p.  804 ;  Hollemann :  Lehrb.,  org.  Chem.,  2te  Aufl.,  p.  205  ; 
See  also  Staedeler  and  Krause :  Jahresb.,  1854,  746;  Hofmeister:  Ann., 
189,  27. 

3.4639  grams  pure  crystallized  copper  sulphate. 
Water  to  make  50  cc. 

17.3  grams  sodium  potassium   tartrate    (Rochelle   salt). 
5.0  grams  sodium  hydroxide. 
Water   to   make   50   cc. 

For  the  quantitative  determination  of  reducing  sugars  Feh- 
ling's  solution  must  be  prepared  accurately  in  accordance  with 
the  directions  given  above,  the  quantities  taken  for  the  pre- 
paration being  usually  ten  times  as  great.  The  alkaline  solu- 
tion of  Rochelle  salt  changes  slowly  on  standing,  however,  and 
it  is  not  advisable  to  use  for  work  intended  to  be  accurate  a 
solution  which  has  stood  for  more  than  a  few  weeks.  For  the 
qualitative  purposes  indicated  here  dissolve  3.5  grams  of  copper 
sulphate  in  50  cc.  of  water,  and  prepare  a  separate  solution  by 
dissolving  17  grams  of  Rochelle  salt  in  15  cc.  of  warm  water, 
adding  15  cc.  of  a  solution  of  sodium  hydroxide  (3  cc.  =  I 
gram),  cooling  and  diluting  to  50  cc.  Equal  volumes  of  the  two 
solutions  may  be  mixed  and  the  mixture  used  for  qualitative 
purposes  at  any  time  within  a  few  hours. 

Prepare  one  per  cent,  solutions  of  sucrose,  maltose,  glucose 
and  lactose  by  dissolving  o.i  gram  of  each  in  10  cc.  of  water. 
Also  prepare  a  solution  of  invert  sugar  (mixture  of  d-glucose 
and  cT-fructose)  by  adding  a  drop  of  concentrated  hydrochloric 
acid  to  5  cc.  of  the  one  per  cent,  solution  of  sucrose,  boiling 
for  about  one  minute,  cooling  and  adding  5  or  6  drops  of  a  10 
per  cent,  solution  of  sodium  hydroxide. 

Put  5  cc.  of  the  mixed  Fehling's  solution  in  a  test-tube,  add 
5  cc.  of  water,  and  one  drop  of  the  one  per  cent,  solution  of 
glucose.  Boil  for  one  minute.  If  no  precipitate  of  red  cuprous 
oxide  appears,  add  more  of  the  sugar  solution  and  boil  again. 
Repeat  the  experiment  with  each  of  the  solutions  prepared. 
Also  add  an  excess  of  the  glucose  solution  to  a  small  portion 


CARBOHYDRATES  187 

of  the  diluted  Fehling  solution  and  note  the  complete  discharge 
of  the  blue  color  after  boiling  and  standing. 

82.  Preparation  of  a  Sugar  by  the  Action  of  an  Enzyme.— 
Maltose  and  Dextrin. 

Literature. — Soxhlet :  J.  prakt.  Chem.,  [2],  21,  276;  Herzfeld:  Ann., 
220,  21 1 ;  Ber.,  12,  2120;  Noyes :  jTlVm.  Chem.  Soc.,  26/274;  Hydrolysis 
of  starch  by  acids,  Rolfe  and  Defren :  J.  Am.  Ch.  Soc.,  18,  869. 

100  grams  starch. 
500  cc.  hot  water. 

10  grams  malt. 
30  cc.  water. 

Rub  up  100  grams  of  starch  with  a  small  amount  of  water  in 
a  mortar,  using  just  enough  water  to  form  a  uniform,  rather 
thick  cream,  which  can  be  poured  into  a  liter  flask.  Add  500 
cc.  of  boiling  water  and,  if  necessary,  boil  for  a  few  minutes  to 
form  a  clear,  nearly  transparent  paste.  Cool  to  60°  and  add  10 
grams  of  malt  which  has  been  digested  for  a  short  time  with 
tepid  water.  Maintain  the  temperature  at  60°  for  20  minutes 
by  immersion  in  a  water-bath  of  that  temperature.  Filter  on  a 
plain  or  plaited  filter.  Put  the  solution  in  a  one  liter  distilling 
bulb,  connect  another  bulb  to  the  side  tube  (Fig.  34,  p.  171)  and 
distil  under  diminished  pressure  till  a  thick  syrup  of  maltose  and 
dextrin  remains.  Add  300-400  cc.  of  alcohol  (sp.  gr.  0.83)  and 
pour  off  the  solution  of  maltose  from  the  precipitated  dextrin. 

The  dextrin  may  be  purified  by  dissolving  in  a  small  amourl 
of  water  and  precipitating  again  with  alcohol  of  the  same  strength 
and  repeating  till  the  solution  of  dextrin  gives  only  a  trifling 
reaction  for  maltose  with  Fehling's  solution  (p.  185).  After 
the  last  precipitation  the  dextrin,  which  precipitates  as  a  gummy 
mass  may  be  rendered  comparatively  dry  and  pulverulent  by 
digesting  it  for  some  time  with  strong  alcohol. 

Unite  the  first  and  second  alcoholic  mother-liquors,  containing 
the  maltose,  distil  away  the  alcohol  and  water  under  diminished 
pressure  till  a  thick  syrup  remains.  Dissolve  this  in  200-300 
cc.  of  hot,  90  per  cent,  alcohol,  filter,  if  necessary,  and  allow 
the  maltose  to  crystallize  from  the  filtrate,  adding  a  very  little 


l88  ORGANIC    CHEMISTRY 

finely  powdered  maltose  to  the  cold  solution  to  start  the  crys- 
tallization. 

Maltose  crystallizes  in  fine  needles,  with  one  molecule  of  water, 
which  is  lost  at  135°.  Its  specific  rotation  calculated  for  anhy- 
drous maltose  is  (a)£  ==  137.04°.  It  reduces  Fehling's  solution 
but  the  copper  factor  is  much  smaller  than  for  glucose. 

The  dextrin  prepared  as  directed  is  not  very  definite  in  its 
properties.  It  has  a  specific  rotation  of  somewhat  more  than 
200°,  and  does  not  reduce  Fehling's  solution. 

83.  Determination  of  the  Specific  Rotation  of  Sucrose  and  of 
Invert  Sugar. 

Literature. — Wiley :  Principles  of  agricultural  analysis,  Vol.  3,  p.  105 ; 
Bulletins  of  U.  S.  Department  of  agriculture  giving  methods  of  analysis 
adopted  by  the  Association  of  Official  Agricultural  Chemists;  Effect  of 
hydrochloric  acid  on  the  rotatory  power  oi  invert  sugar,  Tolman :  J. 
Am.  Chem.  Soc.,  24,  515;  Analysis  of  sugar  mixtures,  Browne:  J.  Am. 
Chem.  Soc.,  28,  439 ;  Specific  rotation,  Noyes :  Org.  Chem.,  p.  47 ;  Effect 
of  temperature  on  the  specific  rotation  of  sucrose,  Wiley:  J.  Am.  Chem. 
Soc.,  21,  568;  Methods  of  the  International  Commission  on  Sugar 
Analysis:  J.  Am.  Chem.  Soc.,  23,  59;  Inversion  by  acid  mercuric  nitrate, 
Cochran:  J.  Am.  Chem.  Soc.,  29,  555. 

Weigh  20  grams  of  the  best  granulated  sugar  or  of  powdered 
rock  candy  in  a  porcelain  dish  or  in  a  sugar  scoop  to  an  ac- 
curacy of  5  mg.  Put  a  funnel  in  the  mouth  of  a  100  cc.  grad- 
uated flask,  rinse  the  sugar  into  the  flask,  make  up  the  volume 
to  about  90  cc.  and  shake  till  the  sugar  is  completely  dissolved, 
make  the  solution  up  to  exactly  100  cc.,  mix  thoroughly  and  filter 
on  a  dry  filter,  if  the  solution  is  not  absolutely  clear,  rejecting 
the  first  20  cc.  of  the  filtrate  (why?)  and  collecting  the  remainder 
in  a  dry  flask.  Fill  a  I  or  2  decimeter  polarimeter  tube  with  the 
solution,  determine  the  angle  of  rotation  with  sodium  light  and 
calculate  the  specific  rotation.  The  value  found  will  usually  be 
a  little  too  low  because  the  sugar  is  not  quite  pure. 

Take  exactly  50  cc.  of  the  solution,  add  5  cc.  of  concentrated 
hydrochloric  acid  and  immerse  the  flask  containing  the  mixture 
in  a  bath  at  67°  for  15  minutes,  cool,  transfer  to  a  100  cc.  meas- 
uring flask,  fill  to  the  mark,  mix  thoroughly  and  determine  the 
rotation  and  specific  rotation  for  invert  sugar  as  before.  If  a 


CARBOHYDRATES  189 

flask  graduated  at  50  and  55  cc.  is  available,  this  may  be 
used  instead  of  following  the  directions  given  and  the  second 
readings  may  be  taken  in  a  tube  no  or  220  mm.  long.  The 
temperature  at  which  the  readings  for  the  invert  sugar  are 
taken  must  be  noted  carefully. 

On  the  basis  of  the  results  found  explain  Herzfeldt's  formula 
for  determining  sucrose  in  the  presence  of  other  sugars  not  af- 
fected by  acids  under  the  conditions  of  inversion  given.     The 
formula  is  (Z.  Riibenzucker-Ind.,  40,  194)  : 
a  —  b 


141.85  +  0.05^ —  T/2 
S   =   Per  cent,  sucrose. 
a  —   Direct  reading. 
b  =  Invert  reading. 
T  =  Temperature. 

The  readings  a  and  b  are  for  an  instrument  such  that  the 
normal  weight  of  pure  sugar  (26.  grams  in  100  cc.)  would  give 
a  reading  of  100.  The  reading  b,  which  is  usually  negative,  is 
to  be  taken  in  the  formula  with  its  appropriate  algebraic  sign. 

Why  can  white  light  be  used  with  the  ordinary  saccharimeters 
having  a  quartz  compensation  system,  while  sodium  light  must 
be  used  for  instruments  reading  with  angular  degrees?  Can 
the  quartz  compensation  instrument  be  properly  used  for  the 
determination  of  specific  rotation  in  general? 

84.  Schweitzers  Reagent.     Solution  of  Cellulose. 

Literature — Watts  Chemical  Diet.,  Vol.  i,  p.  714;  Erdmann :  J.  prakt. 
Chem.,  76,  385 ;  Bumcke  and  Wolfenstein  :  Ber.,  32,  2494,  2502. 

10  grams  crystallized  copper  sulphate. 

150  cc.  water. 

5  cc.  ammonium  chloride  solution   ( 10  per  cent.). 

Sodium  hydroxide   (10  per  cent.). 

30  cc.  ammonium  hydroxide   (0.90). 

Dissolve  10  grams  of  crystallized  copper  sulphate  in  150  cc. 
of  warm  water,  add  5  cc.  of  a  solution  of  ammonium  chloride 
(TO  per  cent.),  cool  thoroughly  and  add  a  ten  per  cent,  solution 


190  ORGANIC    CHEMISTRY 

of  sodium  hydroxide  in  excess.  Wash  the  precipitated  copper 
hydroxide  at  first  by  decantation  and  then  thoroughly  on  a 
plate.  Dissolve  the  precipitate  in  30  cc.  of  ammonium  hydroxide 
(sp.  gr.  0.90)  and  filter  on  glass  wool  or  asbestos.  Dissolve 
some  filter-paper  or  cotton  in  the  reagent,  filter  and  precipitate 
the  cellulose  with  dilute  hydrochloric  or  sulphuric  acid. 

The  solution  of  cellulose  in  Schweitzer's  reagent  destroys  the 
organized  structure,  of  course,  and  the  precipitate  obtained  with 
acids  is  amorphous.  It  is  somewhat  uncertain  whether  the 
chemical  nature  of  the  cellulose  is  changed  by  the  process  or 
not. 

8^.  Preparation  of  Furfural  from  a  Pentose. 
CH  —  CH 

II  .11 

CH        C  —  CHO. 

\/ 

O 

Literature — Hill:  Am.  Chem.  J.,  3,  33;  Stone:  Ber.,  24,  3019;  Am. 
Chem.  J.,  13,  73,  348;  Gunther,  de  Chalmot  and  Tollens :  Ber.,  23, 
3575 ;  Stone  and  Tollens :  Ann.,  249,  227 ;  Allen  and  Tollens :  Ibid,  260,  291 ; 
Stone:  J.  Anal.  Appl.  Chem.,  5»  421. 

100  grams  cobs  of  Indian  corn. 

500  cc.  hydrochloric  acid  (sp.  gr.  1.06). 

Put  in  a  liter  distilling  bulb  100  grams  of  coarsely  powdered 
corn  cobs  (or  wheat  straw,  or  wheat  bran,  but  the  yield  will  be 
smaller),  and  500  cc.  of  hydrochloric  acid,  of  specific  gravity 
i. 06  (140  cc.  acid  of  sp.  gr.  1.19,  and  360  cc.  of  water).  Fit 
in  the  mouth  of  the  bulb  a  cork  bearing  a  dropping  funnel, 
and  connect  with  a  condenser.  He'at  to  boiling,and  distil  slowly, 
at  the  rate  of  about  200  cc.  in  an  hour,  dropping  in  dilute  hydro- 
chloric acid  (75  cc.  acid  sp.  gr.  i.n,  to  500  cc.  of  water),  at 
such  a  rate  as  to  keep  the  contents  of  the  bulb  constant  in  vol- 
ume. Continue  the  distillation  for  three  hours,  or  till  600-700 
cc.  have  distilled.  Add  a  drop  of  methyl  orange,  and  nearly 
neutralize  the  distillate  with  a  strong  solution  of  caustic  soda : 
add  150  grams  of  salt,  and  distil  off  about  200  cc.  Add  60  grams 
of  salt  to  the  distillate,  and  extract  with  ether.  Dry  the  solu- 


CARBOHYDRATES  19! 

tion  with  calcium  chloride,  distil  off  the  ether,  and  distil  the 
furfural  which  remains.  Yield  n  to  12  grams. 

Certain  gums  contained  in  the  materials  used  are  hydrolyzed 

CH2OH 
CHOH 

by  the  dilute  acid,    with  the  formation  of  a  pentose,    CHOH  . 

CHOH 
CHO 

The  pentose  then  condenses  to  furfural. 

Furfural  is  a  colorless  oil,  which  boils  at  161°,  and  has  a 
specific  gravity  of  1.1636  at  13.5°.  Its  odor  resembles  that  of 
benzaldehyde.  By  boiling  with  potassium  cyanide,  in  dilute  al- 

C4H30  —  CHOH 

coholic  solution,  it  is  converted  into  furoin,  ,  in 

C4H30  -.CO 

the  same  manner  in  which  benzaldehyde  is  converted  into  benzoin 
(see  37,  p.  97).  It  condenses  easily  with  ammonia  in  aqueous 
solution  to  furfuramide,  (C5H4O)3N2,  which  is  difficultly  solu- 
ble. It  gives  a  hydrazone  with  phenyl  hydrazine,  and  gives  a  red 
compound  with  aniline  acetate.  Filter-paper  moistened  with  ani- 
line acetate,  furnishes  a  very  sensitive  qualitative  test  for  fur- 
fural. 

86.  Preparation  of  an  Osazone. — Glucosazone. 

CH2OH 

I 
CHOH 

I 
CHOH 

(Dextrosazone,  levulosazone). 
CHOH 

C  =  N  —  NHC6H5 

| 

CH  ==  N  —  NHC6H5 

Literature — E.  Fischer:  Ber.,  17,  580;  Jaksch :  Z.  anal.  Chem.,  24,  478; 
Beythien :  Ann.,  255,  218. 


IQ2  ORGANIC    CHEMISTRY 

2  grams  glucose. 

4  grams  phenyl  hydrazine. 

10  cc.  acetic  acid  (30  per  cent.). 

50  cc.  water. 

Dissolve  2  grams  of  glucose  in  50  cc.  of  water,  add  a  solution 
of  4  grams  of  phenyl  hydrazine  in  10  cc.  of  acetic  acid,  and  heat 
on  a  water-bath  for  two  hours.  Cool,  filter  off  the  glucosazone 
and  recrystallize  it  from  80  per  cent,  alcohol. 

Glucosazone  melts,  when  heated  quickly,  at  200°,  and  crystal- 
lizes' in  characteristic  yellow  needles.  With  diphenylhydrazine 
glucose  gives  an  even  more  characteristic  hydrazone.  (Stahel: 
Ann.,  258,  244.) 

87.  Preparation  of  Levulinic  Acid  by  the  Action  of  a  Dilute 
Acid  on  a  Carbohydrate,  CH3COCH2CH2CO2H. 

Literature — Noeldecke:  Ann.,  149,  224,  228;  Bente:  Ber.,  8,  416;  Tol- 
lens  and  Kehrer:  Ann.,  i75>  181 ;  206,  207 ;  Conrad:  Ber.,  n,  2178; 
Wolff:  Ann':,  208,  105;  Kent  and  Tollens :  Ibid,  227,  229;  Conrad 
and  Guthzeit:  Ber.,  18,  442;  19,  2572;  Neugebauer:  Ann.,  227,  99;  Risch- 
bieth:  Ber.,  20,  1773;  Wehmer  and  Tollens:  Ann.,  243,  314;  Seissl :  Ibid, 
249,  275;  Fittig:  Ber.,  29*  2583. 

100  grams  sugar. 

400  cc.  water 

too  cc.  concentrated  hydrochloric  acid. 

,  Put  in  a  750  cc.  flask  100  grams  of  cane-sugar,  400  cc.  of 
water,  and  100  cc.  of  concentrated  hydrochloric  acid.  Close  the 
flask  with  a  tube  containing  water  as  in  the  preparation  of  cam- 
phoric acid  (see  p.  122).  Heat  on  a  water-bath  for  20  hours 
Filter  on  a  plate,  boil  the  residue  of  humus  with  100  cc.  of 
water  and  filter.  To  the  combined  filtrates  add  a  solution  of  35 
grams  of  sodium  hydroxide,  and  evaporate  to  about  100  cc. 
Filter  again,  if  necessary,  and  extract  four  or  five  times  with 
50-75  cc.  of  ether,  distilling  the  ethereal  extract  and  using  the 
same  ether  each  time.  For  such  cases  it  is  convenient  to  put  a 
dropping  funnel  through  the  stopper  of  the  distilling  bulb  so 
that  the  ether  may  be  introduced  continuously  and  without  re- 
moving the  bulb  from  the  water-bath.  A  funnel  should  be  placed 
in  the  mouth  of  the  dropping  funnel  to  facilitate  the  pouring 


CARBOHYDRATES  193 

of  the  ether,  and  care  must  always  be  taken  to  avoid  ignition  of 
the  latter. 

After  distilling  off  the  ether,  transfer  the  residue  to  a  smaller 
distilling  bulb,  and  distil  under  diminished  pressure,  raising  the 
temperature  of  the  oil  or  air-bath  slowly.  Collect  the  portion 
boiling  at  i4O°-i6o°  under  15  mm.,  or  at  i6o°-i8o°  under  80-100 
mm.  Put  this  portion  in  a  wide-mouthed,  tightly  stoppered  bot- 
tle and  allow  to  stand  at  o°  for  some  time,  till  it  has  solidified 
as  far  as  possible.  Pour  off  the  liquid  part,  warm  the  residue 
gently  till  it  melts,  and  allow  it  tc  crystallize  slowly  at  ordinary 
temperatures.  After  draining  off  the  liquid  part  the  solid  acid 
will  be  nearly  pure.  Yield  10-15  grams. 

The  reactions  which  take  place  are,  first,  the  inversion  of  the 
cane-sugar  to  levulose  and  glucose,  and  then  the  decomposition  of 
these  into  levulinic  and  formic  acids  and  water. 

CH2OH 

CHOH 

CHOH 

CHOH    CH.COCH.CH.CO.H  +  HCO2H  +  H,O. 

CHOH 
CHO 

Levulinic  acid  melts  at  33°,  and  boils  with  slight  decomposi- 
tion at  245°-246°  under  760  'mm.  pressure,  or  I48°-I49°  under 
15  mm.  If  heated  for  some  time  a"t  its  boiling-point,  it  is  con- 
verted into  a  mixture  of  a-  and  ^-angelica  lactones, 

CH3—  C  =  CH  —  CH2CO  and  CH,=  C—  CH.,CH2—  CO. 

i  i  I 

O H  O 1 

It  gives  with  phenylhydrazine  a  crystalline  hydrazone,  and  is 
reduced  to  y-hydroxyvaleric  acid  by  sodium  amalgam.  On  acidi- 
fying a  solution  of  the  sodium  salt  of  this  acid,  valerolactone 
separates. 


Chapter    XI 

HALOGEN  COMPOUNDS 

Chlorine  and  bromine  derivatives  of  the  hydrocarbons  may  be 
obtained  by  the  direct  action  of  the  elements  on  the  hydro- 
carbons. In  the  fatty  acid  series  of  hydrocarbons  this  method  of 
preparation  is  of  scarcely  more  than  theoretical  interest,  partly 
because  the  hydrocarbons  are  difficult  to  obtain  in  pure  condition, 
and  partly  because  both  primary  and  secondary  halogen  alkyls  are 
formed,  and  frequently  di-  and  tri-substitution  products  as  well. 
If  a  complete  replacement  of  the  hydrogen  by  chlorine  or 
bromine  is  desired,  the  addition  of  a  small  amount  of  iodine  great- 
ly facilitates  the  action.  (For  the?  chlorination  of  butane  from 
petroleum,  see  Mabery:  Am.  Chem.  J.,  19,  247.) 

In  the  aromatic  series  direct  replacement  of  hydrogen  by 
chlorine  or  bromine  takes  place  easily,  and  pure  products  are 
readily  obtained.  In  this  series,  also,  the  presence  of  some  sub- 
stances greatly  facilitates  the  reaction,  the  compounds  most  fre- 
quently used  for  the  purpose  being  ferric  chloride  or  bromide. 

The  action  of  chlorine  or  bromine  on  aromatic  hydrocarbons  in 
the  cold  and  dark,  but  with, the  addition  of  ferric  chloride  or 
bromide,  (or  some  powdered  iron),  causes  a  substitution  of  the. 
hydrogen  in  the  nucleus,  anfl  usually  in  the  para  or  ortho  posi- 
tion with  reference  to  the  side  chain.  In  the  sunlight,  or  with  the 
boiling  hydrocarbon,  the  substitution  takes  place  in  the  side  chain. 
(Beilstein  and  Geitner:  Ann.,  139,  331;  Jackson:  Am. Chem.  J., 
i,94:  2,  i.) 

The  monohalogen  derivatives  of  saturated  hydrocarbons  are 
usually  most  easily  obtained  from  the  corresponding  alcohols 
by  treatment  with  phosphorus  trichloride,  tribromide  (or  red 
phosphorus  and  bromine),  or  pentaiodide, 

3ROH  +  PBr3  =  3RBr  +  H,PO3. 
5ROH  +  5!  +  P  =  sRI  +  H3PO4  +  H2O: 

Dihalogen  substitution  products  are  often  obtained  from  hy- 


HALOGEN    COMPOUNDS  IQ5 

drocarbons  of  the  ethylene  series  by  direct  addition,  giving  com- 
pounds in  which  the  halogen  atoms  are  combined  with  adjacent 
carbon  atoms.  They  may  also  be  obtained  from  ketones  or 
aldehydes  by  treatment  with  phosphorus  pentachloride  or  penta- 
bromide,  giving  compounds  in  which  the  halogen  atoms  are  com- 
bined with  the  same  carbon  atom. 

R\  R\ 

>  CO  +  PC15  =      >  CC1,  4  POC13. 

R/  R/ 

Monohalogen  derivatives  of  the  ethylene  series  may  be  pre- 
pared by  treating  di-halogen  derivatives  of  the  marsh  gas  series 
with  alcoholic  potash  or  soda. 

CMH2nBr2  +  KOH  =  aH^Br  -j-  KBr  -f  H2O. 

In  the  aromatic  series  halogen  derivatives  are  often  prepared 
from  the  amines  by  passing  through  the  diazonium  compounds 
( Sandmeyer's  reaction ) . 

RNH2HC1  -f  HN02  RN  =  N  -f  2H2O. 

I 
Cl 

RN  =  N  +  Cu2Cl,  =  RC1  +  N2-h  Cu2Cl2. 
Cl 

Finely  divided  metallic  copper  may  be  used  in  place  of  the 
cuprous  chloride  (Gattermann's  reaction). 

For  iodine  derivatives  a  very  clean  reaction  can  often  be  ob- 
tained by  mixing  such  an  acid  diazonium  solution  as  is  described 
on  pp.  201  and  131  or  one  containing  somewhat  more  acid,  with 
an  excess  of  potassium  iodide  and  warming  the  solution. 

The  action  of  hypochlorites,  hypobromites,  or  hypoiodites  upon 
some  organic  compounds  causes  a  substitution  of  halogen  atoms 
for  hydrogen,  a  reaction  which  is  of  very  great  technical  im- 
portance in  the  preparation  of  chloroform  and  iodoform.  In  the 
former  case,  when  acetone  is  used,  three  hydrogen  atoms  in  one 
of  the  methyl  groups  appear  to  be  at  first  replaced  by  chlorine. 
2CH3  —  CO  —  CH3  +  3Ca02Cl2  =  2CC13COCH3  +  3Ca(OH)2. 

The   accumulation   of   negative   atoms    appears   to   render  the 


196  ORGANIC    CHEMISTRY 

trichloracetone  unstable  toward  bases,  and  it  decomposes  in  a 
manner  which  recalls  the  "acid  decomposition"  of  ^-ketonic 
acids  (see  112). 

2CC13COCH3  +  Ca(OH)2  ==  2CHC13  +  Ca(CH3CO2)2. 

Most  of  the  methods  given  for  the  preparation  of  halogen  de- 
rivatives of  hydrocarbons  may  also  be  used  for  the  preparation 
of  halogen  derivatives  of  other  carbon  compounds. 

Halogen  derivatives  of  acids  are  prepared  by  treating  the 
acid,  or,  in  many  cases,  either  the  chloride  or  bromide  of  the 
acid,  with  the  free  halogen.  Unless  the  temperature  is  unduly 
raised  so  as  to  cause  secondary  reactions,  aliphatic  acids  give  by 
this  treatment  only  a  derivatives.  (Erlenmeyer:  Ber.,  14,  1318; 
Hell :  Ibid,  14,  891 ;  Auwers :  Ibid,  24,  2209,  2233 ;  Michael :  J. 
prakt  Chem.  [2],  36,  92;  Volhard :  Ann.,  242,  161.) 

3O,H2W  +  IC02H  -|-  P  +  nBr  =  3C,,H2WBrCOBr  + 
HP03  +  5HBr. 

ft  derivatives  may  usually  be  obtained  by  treating  aft  unsat- 
urated  acids  with  the  halogen  acids.  Bisubstitution  products  are 
obtained  by  the  addition  of  the  free  halogen  to  unsaturated 
acids. 

The  direct  treatment  of  aromatic  acids  with  halogens  gives 
chiefly  meta  compounds. 


88.  Preparation  of  an  Iodine  Derivative  of  a  Hydrocarbon  from 
an  Alcohol. — Methyl  iodide,  CH3I. 

Literature.— Dumas,  Peligot :  Ann.,  13,  78;  Rieth,  Beilstein :  Ibid,  126, 
250;  Walker:  J.  Chem.  Soc.,  61,  717. 

3   grams   red  phosphorus. 
9  grams  methyl  alcohol. 
25  grams  iodine. 

Place  in  a  50  cc.  distilling  bulb  3  grams  of  red  phosphorus, 
add  9  grams  (n  cc.)  of  methyl  alcohol,  and  then,  in  small  por- 
tions, and  with  careful  cooling  25  grams  of  iodine.  Allow  the 
mixture  to  stand  in  cold  water  for  an  hour  and  then  distil  from 
the  water-bath;  using  a  good  condenser.  Shake  the  distillate 


HALOGEN   COMPOUNDS    •  197 

twice  with  an  equal  volume  of  water,  separating  with  a  separa- 
tory  funnel  (see  51,  p.  127),  add  once  more  an  equal  volume  of 
water  and,  with  frequent  shaking,  caustic  soda  till  the  methyl 
iodide  is  colorless.  Separate  again,  transfering  the  iodide  to  a 
small  distilling  bulb,  add  some  fused,  powdered  calcium  chloride 
and  distil  again  from  the  water-bath  after  about  an  hour,  using 
a  thermometer.  Yield  20-25  grams. 

Methyl  iodide  boils  at  42.8°,  and  has  a  specific  gravity  of 
2.2852  at  15°,  or  2.2529  at  25°.  On  heating  with  fifteen  parts  of 
water  at  100°  it  is  converted  into  methyl  alcohol  and  hydriodic 
acid. 

Because  of  its  low  boiling-point  and  high  molecular  weight 
it  escapes  rapidly  unless  kept  in  small  bottles  tightly  stoppered 
with  cork  stoppers,  or,  better,  in  sealed  tubes.  A  globule  of 
mercury  is  sometimes  placed  in  the  bottle  to  remove  iodine.  For 
the  preparation  of  large  quantities  of  ethyl  or  methyl  iodide 
the  method  of  Walker  (he.  cit.)  is  to  be  recommended. 

89.  Preparation  of  a  Bromine  Derivative  of  a  Hydrocarbon 
from  an  Alcohol  with  Sulphuric  Acid  and  Potassium  Bromide. 
-Ethyl  bromide,  C2H5Br. 

Literature — Serullas :  Ann.  chim.  phys.  [2],  34*  99,  (1827);  Loewig: 
Ann.,  3i  288;  Perkin :  J.  prakt.  Chem.,  [2],  3*,  497;  R-  Schiff:  Ber.,  i9i 
563;  Riedel:  Ibid,  24,  R.  105. 

90  grams  potassium  bromide. 
70  cc.  water. 

loo  cc.   alcohol. 

100  cc.  concentrated  sulphuric  acid. 

10  cc.  water. 

Put  100  cc.  of  concentrated  sulphuric  acid  in  a  flask,  add  slowly 
with  constant  shaking,  but  within  two  or  three  minutes,  100  cc. 
of  alcohol.  Cool  thoroughly  and  pour  the  mixture  into  a  400  cc 
distilling  bulb  or  flask  containing  90  grams  of  potassium  bro- 
mide, and  70  cc.  of  water.  Distil  quite  rapidly,  heating  on  a 
wire  gauze  covered  with  a  thin  sheet  of  asbestos  and  using  a 
good  condenser,  as  long  as  ethyl  bromide  comes  over.  A  little 


198  ORGANIC    CHEMISTRY 

water  should  be  placed  in  the  receiver  to  absorb  some  hydro- 
bromic  acid,  which  is  given  off.  Separate  the  ethyl  bromide 
irom  the  aqueous  layer  and  add  to  it,  with  careful  cooling, 
concentrated  sulphuric  acid  till  the  acid  separates  below.  This 
will  remove  any  ether  which  has  been  formed.  Separate  again, 
wash  twice  with  a  small  amount  of  water,  put  the  bromide  in  a 
distilling  bulb  with  some  fused,  powdered  ca1cium  chloride  and 
distil,  with  a  thermometer,  after  one  or  two  hours.  Yield  55  to 
60  grams. 

The  reactions  involved  in  the  preparation  are  as  f  o'-lows . 
C2H5OH  +  H2S04  C2H5HS04  -j-  H2O 

Ethyl  sul- 
phuric acid 

C2H5HS04  +  KBr  C2H5KSO4  +  HBr 

Ethyl  potas- 
sium sulphate 

C2H5KSO4  -f  HBr     =     CaH5Br  +  HKSO4. 

Ethyl  bromide  may  also  be  prepared  by  the  action  of  bromine 
on  red  phosphorus  and  alcohol,  but  the  method  here  given  is 
more  satisfactory  and  gives  a  purer  product,  unless  red  phos- 
phorus free  from  arsenic  is  available. 

Ethyl  bromide  boils  at  38.4°,  and  has  a  specific  gravity  of 
1.476  at  15°.  It  must  be  kept  in  tightly  corked,  not  glass  stop- 
pered bottles. 

Ethyl  bromide  is  sometimes  used  as  an  anaesthetic.  For 
this  use  it  must  be  entirely  free  from  arsenic.  Arsenic,  if  pres- 
ent, may  be  detected  by  burning  the  substance  in  a  small  spirit 
lamp,  and  drawing  the  products  of  combustion  through  a  solution 
of  caustic  soda.  The  solution  may  then  be  tested  for  arsenic 
by  means  of  hydrochloric  acid  and  a  concentrated  solution  of 
stannous  chloride. 

90.  Preparation  of  a  Bromine  Derivative  of  an  Aromatic  Hy- 
drocarbon.— Para-dibrombenzene. 

/Br  (i) 
C6H/ 

XBr  (4) 

Literature — Couper :  Ann.  chim.  phys.  [3],  52,  309,  (1858)  ;  Riese :  Ann., 
164,  162;  Jannasch:  Ber.,  10,  1355. 


HALOGEN   COMPOUNDS  199 

50  grams  benzene    (,56.5  cc.). 

210  grams  bromine   (67  cc.). 

i  gram  iron  filings. 

Put  50  grams  of  benzene  in  a  dry,  200  cc.  flask.  Add  i  gram 
of  iron  filings  or  turnings,  and  close  the  mouth  with  a  stopper 
bearing  a  dropping  funnel  which  dips  below  the  surface  of  the 
benzene,  an  1  an  exit  tube.  Put  in  the  dropping  funnel,,  best  out 
of  doors,  67.  cc.  of  bromine.  Place  the  flask  in  a  water-bath 
filled  with  cold  water,  and  connect  the  exit  tube  with  a  tube 
opening  just  above  the  surface  of  water  in  a  large  bottle.  Allow 
the  bromine  to  flow  slowly  into  the  benzene.  Toward  the  end, 
aid  the  reaction  by  heating  the  water-bath  slowly  to  the  boiling- 
point. 

When  the  reaction  is  complete  and  no  more  vapors  o-f  bromine 
appear,  distil  from  the  flask  or  from  a  distilling  bulb,  collect- 
ing the  portion  boiling  at  2oo°-23O°  by  itself.  Crystallize  from 
a  small  amount  of  alcohol.  Yield  50  to  60  grams  of  p-dibrom- 
benzene. 

Para-dibrombenzene  crystallizes  in  white  prisms  or  leaflets 
which  melt  at  89°,  and  boil  at  219°. 

91.  Substitution  of  Chlorine  in  the  Side  Chain  of  an  Aromatic 
Hydrocarbon.— Benzyl  chloride,  C6H5CH2C1. 

Literature.— Cannizzaro :  Ann.,  96,  246;  Beilstein,  Geitner :  Ibid,  i39» 
332;  Lauth,  Grimaux  :  Ibid,  M3»  80;  Schramm :  Ber.,  18,  608:  Haase :  Ibid, 
26,  1053. 

loo  grams  toluene. 

100  grams   manganese   dioxide. 

540  Cc.  commercial  hydrochloric  acid. 

Put  in  a  200  cc.  flask  100  grams  (115  cc.)  of  toluene  and  con- 
nect it  with  an  upright  condenser.  Place  in  the  upper  end  of  the 
condenser  a  tight  stopper  bearing  two  glass  tubes,  one  passing 
just  through  the  stopper  and  the  other  reaching  nearly  to  the 
bottom  of  the  flask.  Connect  the  first  tube  with  a  tube  opening 
just  above  the  surface  of  water  in  a  'bottle.  Or  arrange  one 
tube  passing  through  the  stopper  beside  the  condenser,  and  con- 
nect the  other  with  the  top  of  the  condenser,  as  in  Fig.  38 


200 


ORGANIC    CHEMISTRY 


Heat  the  toluene  to  boiling  and  pass  in  chlorine  generated  in  a 
liter  flask  by  the  slow  addition  of  540  cc.  of  commercial  hydro- 
chloric acid  to  loo  grams  of  manganese  dioxide,  the  mixture  be- 
ing warmed  gently  and  the  gas  purified  by  passing  it  through  a 
wash-bottle  containing  water,  and  then  through  one  containing 
concentrated  sulphuric  acid.  The  operation  must  be  carried  out 
in  clearjdaylight,  or,  if  possible,  in  the  direct  sunlight. 


Fig.  38. 

When  the  evolution  of  chlorine  has  ceased,  submit  the  product 
in  the  flask  to  fractional  distillation.  The  portion  boiling  below 
150°  consists  chiefly  of  unchanged  toluene  and  may  be  used  for 
a  new  preparation.  After  fractioning  two  or  three  times  the 
portion  boiling  at  i76°-i8i°  will  consist  of  nearly  pure  benzyl 
chloride.  The  yield  varies  according  to  the  brightness  of  sun- 
light in  which  the  operation  is  conducted.  In  some  cases  the 
weight  of  benzyl  chloride  may  equal  that  of  the  toluene  used. 

Benzyl  chloride  is  a  colorless  liquid  with  an  unpleasant  odor. 
Its  vapor  attacks  the  eyes  very  strongly.  It  boils  at  178°  and  has 
a  specific  gravity  of  1.113  at  I5°-  By  long1  boiling-  with  water  it 


HALOGEN   COMPOUNDS  2OI 

is  converted  into  benzyl  alcohol.  Oxidizing  agents  oxidize  it 
to  benzoic  acid.  The  higher  boiling  portions  contain  some  benzal 
chloride,  C6H5CHC12,  which  boils  at  203.5°. 

92.  Preparation  of  a  Bromine  Derivative  of  a  Hydrocarbon  from 
an  Aromatic  Amine. — Parabromtoluene, 

/CH3  (i) 
C6H/  .  ._^ 

||r      (4) 

Literature — Hiibner,  \\~allacri:  Afn'.,  154,  293;  Glinzer,  Fittig:  Ibid, 
J36,  301;  Michaelis,  Genzken :  Ibid,  242,  165;  Ladenburg:  Ber.,  7,  1685; 
Sandmeyer:  Ibid,  17,  2652;  Schramm :  Ibid,  18,  606;  Gasiorowski  u. 
Wayss:  Ibid,  18,  1936;  Gattermann :  Ibid,  23,  1218;  Erdmann :  Ann.,  272, 
141 ;  Heller :  Z.  angew.  Chem.,  23,  389. 

25  grams  copper  sulphate. 
72  grams  potassium  bromide. 

9  grams  (5  cc.)  sulphuric  acid  (1.84). 

10  grams  reduced  copper  or  copper  bronze,  "Natur  Kupfer  C." 
160  grams  water. 

21.4  grams   para-toluidine. 

80  cc.  water. 

29  grams  sulphuric  acid    (15.7  cc). 

100  grams  ice. 

14  grams  sodium  nitrite. 
70  cc.  water. 

In  a  liter  flask  put  25  grams  (i  mol.)  of  crystallized  copper  sul- 
phate, 72  grams  (6  mols.)  of  potassium  bromide,  100  cc.  of  water, 
10  grams  of  reduced  copper,  or  copper  bronze,  "Natur  Kupfer 
C,"  and  9  grams  (5  cc.,  i  mol.)  of  concentrated  sulphuric  acid. 
Heat  on  an  asbestos  plate  with  an  upright  condenser  to  gentle 
boiling  till  the  solution  is  colorless.  Meanwhile  put  in  a  beaker 
21.4  grams  (2  mols.)  of  paratoluidine,  add  80  cc.  of  water  and 
29  grams  (15.7  cc.,  3  mols.)  of  concentrated  sulphuric  acid. 
The  toluidine  should  dissolve  in  the  hot  solution  to  insure  its 
complete  conversion  into  the  sulphate.  Stir  and  cool  till  the 
sulphate  has  separated  in  finely  divided  condition.  Add  100 
grams  of  ice  and.  when  the  temperature  has  fallen  to  o°.  add 


202  ORGANIC    CHEMISTRY 

slowly,  with  stirring,  14  grams  (2  mols.)  of  sodium  nitrite  dis- 
solved in  70  cc.  of  water.  After  standing  for  five  minutes  the 
solution  should  react  for  nitrous  acid  when  a  drop  is  placed 
on  starch  potassium  iodide  paper.  If  it  does  not,  a  little  more 
of  the  nitrite  must  be  added,  but  the  least  possible  excess  must 
be  used.  Neither  the  diazonium  solution,  nor  that  of  the  cup- 
rous bromide  should  be  allowed  to  stand  long  after  they  are 
prepared,  because  of  the  tendency  of  the  former  to  decompose. 
and  of  the  latter  to  oxidize. 

Cool  the  cuprous  bromide  solution  very  slightly,  and  add  the 
diazonium  solution  slowly,  shaking  vigorously  and  warming  the 
solution  on  a  vigorously  boiling  water-bath.  The  whole  of  the 
solution  should  be  added  within  two  to  three  minutes,  if  possible 
without  cooling  it  too  far.  The  diazonium  solution  is  best  add- 
ed through  a  funnel  with  a  long,  wide  stem  dipping  beneath  the 
cuprous  bromide  solution. 

It  is  impossible  in  any  case,  apparently,  to  secure  a  perfectly 
clean  reaction.     Three  different   reactions  may  take  place: 
=  N  +  H20  =  C7H7OH  +  N,+  HBr. 


Br 
N  +  Cu2Br2  C7H7N=NC7H7+  N2+  2CuBr2. 

Br 
C7H7N  =  N  +  Cu2Br2  C7H7Br  +  N2+  Cu,Br,. 

Br 

The  first  reaction  takes  place  if  the  diazonium  solution 


poses  before  it  is  added  to  the  cuprous  bromide,  or  if  it  is  added 
to  the  hot  solution  in  such  a  manner  that  it  is  not  immediately 
mixed  with  it,  so  that  the  diazonium  compound  has  no  oppor- 
tunity to  combine  with  the  cuprous  bromide.  Hence  the  neces- 
sity of  vigorous  shaking  to  secure  a  rapid  and  thorough  mixture 
of  the  solutions.  The  second  reaction  is  apparently  favored 
when  the  diazonium-cuprous  bromide  remains  in  the  cool  solu- 
tion undecomposed.  The  best  conditions  for  the  reaction  appear 
to  be  secured  at  the  lowest  temperature  of  rapid  decomposition 


HALOGEN    COMPOUNDS  2O3 

for  the  diazonium-cuprous  compound.  This  temperature  varies 
in  different  cases.  It  is  much  higher  for  toluene  para  diazonium- 
cuprous  bromide  than  for  the  ortho  compound,  apparently  be- 
cause of  the  greater  stability  of  the  former.  (See  Erdmann:  loc. 

«•*.) 

When  the  diazonium  solution  has  all  been  added,  distil  over 
the  parabromtoluene  in  a  rapid  current  of  water  vapor  (see  22,  p. 
71),  shake  it  with  some  sodium  hydroxide  solution  to  remove  any 
paracresol  present,  separate  it  from  the  solution,  dry  by  allowing 
it  to  stand  for  some  time  with  solid  caustic  potash,  pour  off  or 
filter  through  a  dry  filter,  and  distil  from  a  small  distilling  bulb, 
using  a  condensing  tube  or  distilling  slowly  into  a  bottle  or  tube. 
Yield  about  20  grams. 

Parabromtoluene  crystallizes  in  rhombic  plates,  which  melt  at 
28.5°.  It  boils  at  185.2°,  and  has  a  specific  gavity  of  1.3897  at 

20° 

— o  .     Oxidizing   agents  convert  it  into  parabrombenzoic  acid. 
4 

93.  Preparation  of  a  Bromine  Derivative  of  an  Acid.  Hell- 
Volhard-Zelinsky's  Method.— a-Bromobutyric  acid,  CH3CH2CH 
Br.CO.,H.  Bromo  (2)-butanoic  acid. 

Literature — Borodin:  Ann.,  119,  121;  Xaumann :  Ibid,  119,  115;  Hell: 
Ber.,  14*  891;  21,  1726;  Volhard:  Ann.,  242,  141;  Ber.,  21,  1904;  Zelinsky: 
Ibid,  20,  2026:  Auwers  and  Bernhardi :  Ibid,  24,  2216:  Hell  and  Lauber : 
Ibid,  7,  560. 

• 

17.6  grams  butyric  acid. 
2.2  grams  red  phosphorus. 
60  grams  bromine  (20  cc.). 

Select  a  small  Liebig  condenser  whose  inner  tube  will  pass 
just  inside  of  the  neck  of  a  50  cc.  round-bottomed  flask.  Cut 
off  the  lip  of  the  flask,  put  the  end  of  the  condenser  in  its  mouth 
and  connect  by  means  of  a  rubber  tube,  which  slips  over  both, 
as  is  done  with  some  forms  of  condensers.  (See  Fig.  39). 
Put  in  the  flask  2.2  grams  (^3  at.)  of  red  phosphorus,  and  17.6 
grams  (i  mol.)  of  normal  butyric  acid.  Add  slowly  from  a 
dropping  tube  with  a  glass  stop-cock,  or  from  a  bulb  drawn  out 
to  a  capillary  below,  through  the  top  of  the  condenser,  60  grams 


204 


ORGANIC    CHEMISTRY 


(11/s  at.)  of  bromine.  The  bromine  is  best  measured  from  a 
dry  burette  or  measuring  tube,  in  a  good  hood  or  out  of  doors. 
The  top  of  the  condenser  should  be  closed  with  a  doubly  per- 
forated stopper,  one  hole  carrying  the  dropping  tube,  and  the 
other  a  tube  leading  out  of  doors  or  just  over  the  surface  of  a 
solution  of  caustic  soda  in  a  bottle.  Drop  in  the  bromine  slowly, 
and  warm  very  gently  on  a  water-bath  till  the  vapors  of  bromine 
disappear,  usually  about  an  hour.  Cool,  and  pour  the  contents 
of  the  flask,  in  small  portions,  upon  50  grams  of  ice  in  a  flask. 


Fig.  39- 

Shake  vigorously,  keeping  the  contents  of  the  flask  cold,  till  the 
bromide  of  the  bromobutyric  acid  is  decomposed,  and  the  odor  of 
phosphorus  oxybromide  has  disappeared.  Separate  the  acid, 
from  the  aqueous  solution,  wash  it  once  with  a  small  amount 
of  water,  and  distil  it  under  diminished  pressure.  The  portion 
boiling  at  I35°-I4O°,  under  a  pressure  of  35  mm.  will  be  nearly 
pure. 

In  working  with  a  small  amount  of  acid  the  bromination  may 
be  effected  with  advantage  by  putting  a  weighed  quantity  of  the 
acid  in  a  sealed  tube,  converting  it  into  the  chloride  by  the  cal- 


HALOGEN   COMPOUNDS  205 

culated  amount  of  phosphorus  pentachloride,  putting  in  a  bulb 
containing  two  atoms  of  bromine  for  one  molecule  of  the  acid, 
Dealing  the  tube,  breaking  the  bulb  containing  the  bromine  by 
shaking  the  tube,  and  heating,  till  vapors  of  bromine  disappear, 
in  a  water-bath.  On  cooling  and  opening  the  tube  the  phos- 
phorus oxychloride  may  be  decomposed  by  shaking  with  cold 
water  and,  in  case  the  chloride  of  the  acid  is  not  readily  decom- 
posed in  this  way,  it  may  be  taken  up  with  ether,  the  solution 
dried  with  calcium  chloride,  the  ether  distilled,  and  the  chloride 
decomposed  by  warming  with  glacial  formic  acid.  See  Baeyer : 
Ann.,  245,  175;  Aschan:  Ibid,  271,  265. 

a-Bromobutyric  acid  boils  with  some  decomposition  at  212°- 
217°.     It   boils    without    decomposition    at    I36°-I38°    under   a 
pressure  of   35   mm.     The   specific   gravity   at   15°   is    1.54.     It 
dissolves  in  about  15  parts  of  water.  When  treated  with  alcoholic 

H  —  C  —  C02H 
potash  it  is  converted  into  cis-crotonic  acid,  || 

H  —  C  —  CH3 

The  yield  is,  however,  poor,  owing  to  the  formation  of  hydroxy- 
butyric  acid  and  other  substances. 

94.  Preparation  of  the  Bromine  Derivative  of  an  Ester  by  Direct 
Bromination. — Ethyl  ester  of  monobromomalonic  acid. 
Br  C02C2H5 

\  p/ 

/°\ 
H  C02C2H5 

Literature — Knoevenagel:  Ber.,  21,  1356;  Conrad  and  Bruckner:  Ber., 
24,  2997;  Condensation  to  ethylene  tetracarboxylic  ester  (Dicarbintetra- 
carboxyl  ester)  Blank  and  Sampson:  Ber.,  32>  860. 

30  grams  ethyl  malonic  ester. 

30  grams  (9.6  cc.)  bromine. 

Put  in  a  loo  cc.  distilling  bulb  30  grams  of  malonic  ester. 
Insert  in  the  neck  of  the  bulb  a  rubber  stopper  bearing  a  separa- 
tory  funnel.  Put  in  the  separatory  funnel  30  grams  (i  mol. 
=  9.6  cc.)  of  bromine.  Connect  the  side  tube  of  the  bulb  with  a 
tube  which  will  deliver  the  hydrobromic  acid  evolved  over  water 
in  a  500  cc.  bottle  but  the  tube  should  not  dip  below  the  surface 


2C>6  ORGANIC    CHEMISTRY 

of  the  water.  The  whole  operation  should  be  carried  out  in  a 
good  hood.  Drop  the  bromine  into  the  ester  slowly  with  constant 
shaking  and  warming  at  first  to  40° -50°  to  start  the  reaction. 
After  all  of  the  bromine  has  been  added  warm  gently  for  a 
short  time,  on  the  water-bath,  till  the  mixture  becomes  nearly 
colorless.  Cool  thoroughly,  add  in  small  portions  with  constant 
cooling  a  ten  per  cent,  solution  of  sodium  carbonate  till  the  solu- 
tion remains  alkaline  to  litmus  after  shaking.  Transfer  to  a 
separatory  funnel  and  draw  off  the  bromomalonic  ester  below, 
first  filling  the  funnel  nearly  full  of  water  and  agitating  gently  so 
that  none  of  the  heavy  liquid  floats  in  globules  on  the  surface. 
Dry  the  ester  with  calcium  chloride,  pour  off  or  filter  into  a 
Claissen  distilling  bulb  (p.  172)  and  distil  under  diminished 
pressure.  The  portion  boiling  at  I2o°-i25°  under  a  pressure  of 
14  mm.  is  sufficiently  pure  for  most  purposes  but  retains  some 
dibromomalonic  ester  which  cannot  be  entirely  removed  by 
fractionation.  The  diethylester  of  bromomalonic  acid  boils  at 
235°  with  some  decomposition  and  has  a  specific  gravity  of 
1.426  at  15°. 

95.  Preparation  of  a  Chlorine  Derivative  of  a  Hydrocarbon 
by  the  Use  of  Calcium  Hypochlorite. — Chloroform,  CHC13,  trichlo- 
romethane. 

Literature — Soubeiran :  Ann.  chim.  phys.  [2],  48,  131  (1831);  Liebig: 
Ann.,  i,  199;  Belohoubek:  Ibid,  165,  349;  Goldberg:  J.  prakt.  Chem.  [2], 
24,  109  (1881)  ;  Bechamp:  Ann.  chim.  phys.  [5],  22,  347  (1881)  ;  Orndorff 
and  Jessel :  Am.  Chem.  J.,  10,  365 ;  E.  R.  Squibb :  J.  Am.  Chem.  Soc.,  18, 
231. 
.  150  grams  bleaching  powder. 

450  cc.  water. 

12  grams  (16  cc.)  acetone. 
•35  cc.  water. 

Put  in  a  liter  flask  150  grams  of  bleaching  powder  (containing 
33  per  cent,  available  chlorine),  add  450  cc.  of  water,  and  insert 
a  stopper  bearing  a  dropping  funnel,  a  bent  tube  leading  to  a 
condenser,  and  a  third  tube  leading  nearly  to  the  bottom  of  the 
flask.  Introduce  through  the  dropping  funnel,  slowly  and 


HALOGEN    COMPOUNDS  2O1/ 

with  frequent  shaking,  a  mixture  of  16  cc.  of  acetone  with  35  cc. 
of  water.  After  the  acetone  has  all  been  added  and  the  flask  no 
longer  grows  warm  spontaneously,  distil  the  remainder  of  the 
chloroform  by  passing  in  a  current  of  steam.  Shake  the  chlo- 
roform several  times  with  small  quantities  of  water,  separate,  dry 
by  allowing  to  stand  with  fused  calcium  chloride,  and  distil  from 
the  water-bath  without  separating  from  the  calcium  chloride. 
Yield  about  20  grams. 

Chloroform  is  a  colorless  liquid  with  an  ethereal  odor  and  a 
sweetish  taste.  It  boils  at  61°,  and  has  a  specific  gravity  of 

i.  5039  at— 5 —  ,    and  of  1.5264  at— 5-.     Pure    chloroform    de- 
4  4 

composes  slowly,  especially  in  the  sunlight,  with  liberation  of 
chlorine,  hydrochloric  acid,  phosgene,  and  other  substances.*  The 
addition  of  one  per  cent,  of  alcohol  renders  it  more  stable.  Pure 
chloroform  should  not  impart  an  acid  reaction  to  water  with 
which  it  is  shaken,  nor  should  it  react  with  a  solution  of  silver 
nitrate  in  the  cold. 

96.  Preparation  of  an  Iodine  Derivative  of  a  Hydrocarbon  by 
the  Action  of  Iodine  and  Sodium  Carbonate  on  Ethyl  Alcohol. 

• — lodoform,  CHI3,    triiodomethaneu 

Literature — Serullas  :  Ann.  chim.  phys.  [2],  22,  172 ;  25, 311 ;  Bouchardat : 
Ann.,  22,  225 ;  Spindler :  Ann.,  231,  263 ;  Forster,  Meyer :  J.  prakt.  Chem. 
[2],  56,  354;  Elbs,  Herz:  Chem.  Zentralbl,  1897,  II,  695:  Quantitative 
determination,  Greshoff :  Z.  anal.  Chem.,  29,  209 ;  32,  361 ;  Schacherl : 
Chem.-Zentralbl,  1897,  I,  568. 

10  grams  crystallized  sodium  carbonate  (or  3.6  grams  of  the 
anhydrous  salt). 
50  cc.  water. 
10  grams  alcohol. 
10  grams  iodine. 

In  a  loo  cc.  flask  dissolve  10  grams  of  crystallized  sodium  car- 
bonate (or  3.6  grams  of  the  anhydrous  salt)  in  50  cc.  of  warm 
water,  add  10  grams  of  alcohol,  warm  to  7o°-8o°  and  add  in  por- 
tions 10  grams  of  iodine,  but  do  not  add  iodine  after  the  iodine 
color  no  longer  disappears  after  warming  for  a  short  time. 


2C>8  ORGANIC    CHEMISTRY 

Cool,  filter  and  wash  the  iodoform.  Dissolve  it  in  15-20  cc.  of 
ether,  wash  the  solution  twice  with  water,  dry  it  with  calcium 
chloride  and  allow  the  ether  to  evaporate  spontaneously  in  a 
small  beaker  or  crystallizing  dish.  Yield  2-3  grams. 

Iodoform  crystallizes  in  leaflets  or  in  hexagonal  plates  which 
melt  at  119°.  It  is  volatile  with  water  vapor  and  is  a  powerful 
germicide. 


Chapter  XII 

4 

NITRO  COMPOUNDS 

The  nitro  derivatives  of  aromatic  compounds  have  been  long- 
est known  and  are  most  easily  prepared.  For  a  long  time  it  was 
thought  that  nitro  derivatives  of  hydrocarbons  of  the  marsh 
gas  series  could  not  be  prepared  by  the  direct  treatment  of  hy- 
drocarbons with  nitric  acid.  Kon'owalow  has  shown,  however, 
(Ber.,  28,  1852,  and  29,  2199),  tnat  such  compounds  may,  in 
many  cases,  be  prepared  by  the  use  of  dilute  nitric  acid,  and 
nitro  compounds  of  the  homologues  of  benzene  may  be  pre- 
pared containing  the  nitro  group  in  the  side  chain  by  the  same 
method. 

The  method  more  usually  employed  for  the  preparation  of 
nitro  compounds  of  the  aliphatic  series  consists  in  treating  alkyl 
iodides  with  silver-  nitrite. 

RI  +  AgNCX     =     R— NO2  +  Agl. 

With  aromatic  hydrocarbons  nitration  is  effected  sometimes  by 
adding  the  hydrocarbon  or  other  compound  to  the  nitric  acid, 
and  sometimes  by  the  reverse  process. 

RH  +  HNO8  =  RNO2  +  H2O. 

As  the  reaction  is  accompanied  by  a  considerable  evolution  of 
heat,  the  mixture  must  usually  be  made  carefully,  and  in  many 
cases  cooling  is  necessary.  The  strength  of  acid  and  the  tem- 
perature required  vary  greatly  in  different  cases.  Sometimes 
it  is  necessary  to  reinforce  the  acid  by  the  use  of  a  mixture 
with  concentrated  sulphuric  acid.  In  general  it  is  better  to  use 
such  a  mixture  and  moderate  the  action  by  cooling  rather  than  to 
use  nitric  acid  alone  at  a  higher  temperature.  Benzene  deriva- 
tives with  side  chains  are  more  easily  nitrated  than  benzene 
itself. 

The  nitro  group  usually  enters  in  the  para  or  ortho  position 
with  reference  to  CH,,  C2H5,  OH,  NH2,  CI,  Br,  or  I,  but  mainly 
14 


2IO  ORGANIC   CHEMISTRY 

in  the  meta  position  toward  CO2H,  SO3H,  CHO,  CN,  £C13,  or 
NO2.  In  the  case  of  the  amino  group  it  is  sometimes  possible 
to  cause  the  group  to  enter  in  the  ortho  or  meta  position  at  will 
by  changing  the  conditions,  or  by  introducing  the  acetyl  group  in 
the  amino  group. 

In  order  to  secure  a  nitro  group  in  a  desired  position  it  is 
often  necessary  to  introduce  two  groups,  and  then  eliminate  one 
of  them  by  reduction  to  the  amino  group  and  subsequent  elimina- 
tion of  the  latter  through  the  diazonium  reaction. 

R  _  N  =  N  +  C,H5OH  ==  RH  +  C,H4O  -f  HNO3  -f  N,. 

N03 

Primary  and  secondary  nitro  compounds  are  soluble  in  solu- 
tions of  alkalies  with  the  formation  of  salts  having  the  struc- 

xONa 
ture,  =  C  =  NXf  (Nef  :  Ann.,   280,   263;    Ber.,  29,  1218). 


Tertiary  nitro  compounds,  and  nitro  compounds  of  the  aromatic 
series  except  nitrophenols  (Hantsch),  do  not  form  compounds  of 
this  character. 

Mononitro  compounds  of  benzene  and  its  homologues  are 
volatile  with  water  vapor,  and  may  frequently  be  separated  from 
dinitro  compounds  and  other  substances  by  this  means. 

The  reduction  of  nitro  compounds  to  amines  and  other  com- 
pounds will  be  considered  in  the  following  chapter. 

The  nitration  of  toluene  has  already  been  given  on  p.   126. 

97.  Nitration  of  an  Aromatic  Hydrocarbon.  —  Nitrobenzene. 
Literature  —  Mitscherlich  :  Ann.,   12,  305. 

50  grams  of  benzene. 

60  grams  nitric  acid.  (1.42). 

80  grams  sulphuric  acid   (1.84). 

Put  50  grams  of  benzene  in  a  300  cc.  flask.  Drop  in  slowly, 
with  vigorous  shaking  and  during  about  15  minutes  a  cooled 
mixture  of  60  grams  of  nitric  acid  (1.42)  and  80  grams  of  sul- 
phuric acid  (1.84).  Cool  in  running  water  so  that  the  tempera- 
ture does  not  rise  above  5o°-6o°.  When  all  of  the  acid  has 


NITRO    COMPOUNDS  211 

been  added  and  the  temperature  no  longer  rises  on  vigorous 
shaking,  place  the  flask  on  the  water-bath  and  heat  for  half 
an  hour  with  frequent  shaking.  Cool  again,  pour  the  contents 
of  the  flask  into  300  cc.  of  cold  water,  separate  the  nitrobenzene 
from  the  acid  solution,  wash  it  once  with  water,  dry  with  calcium 
chloride  and  distil. 

Nitrobenzene  solidifies  at  a  low  temperature  and  melts  at  5°. 
It  boils  at  210°  and  has  a  specific  gravity  at  2°74^  of  1.2033. 

98.  Preparation  of  a  Dinitro  Compound  by  Direct  Nitration. — 

XN02  (i) 
w-Dinitrobenzene,  C6H4^ 

XN02  (3) 

Literature — Deville:  Ann.  chim.  phys.,  [3],  3»  187  (1841);  Muspratt, 
Hofmann:  Ann.,  57,  214;  Beilstein,  Kurbatow :  Ibid,  176,  43;  Willgerodt: 
Ber.,  25,  608 ;  V.  Meyer,  Stadler :  Ibid,  17,  2649. 

20  grams  benzene  (23  cc.). 

50  cc  nitric  acid  (1.42). 

50  cc.  concentrated  sulphuric  acid. 

loo  cc.  concentrated  sulphuric  acid. 

Put  in  a  300  cc.  flask  20  grams  (23  cc.)  of  benzene  and  add 
in  small  portions  a  cooled  mixture  of  50  cc.  of  nitric  acid  (sp. 
gr.  1.42)  with  50  cc.  of  concentrated  sulphuric  acid.  Shake 
vigorously  after  each  addition  and  cool  somewhat,  to  prevent  too 
violent  a  reaction.  When  the  mixture  has  all  been  added  and 
the  whole  shaken  vigorously  for  some  minutes,  add  in  small  por- 
tions and  shaking  as  before,  but  without  cooling,  100  cc.  of  con- 
centrated sulphuric  acid.  Heat  to  about  120°,  allow  to  cool  to 
about  80°,  and  pour,  with  stirring,  into  1500  cc.  cold  water.  Fil- 
ter off  the  dinitrobenzene  and  crystallize  from  alcohol.  Yield 
30  to  32  grams. 

Metadinitrobenzene  crystallizes  in  needles  which  are  colorless 
and  odorless.  It  melts  at  91°  and  boils  without  decomposition 
at  297°.  100  parts  of  alcohol  at  20°  dissolve  3.5  parts.  Easily 
soluble  in  hot  alcohol.  Practically  insoluble  in  water. 


or 


212  ORGANIC    CHEMISTRY 

NO, 


99.  a-Nitronaphthalene, 


Literature  —  Laurent:  Ann.  chim.  phys.,  [2],  59,  378;  Beilstein,  Kuhlberg: 
Ann.,  169,  83  ;  Liebermann  :  Ibid,  183,  235  ;  Piria  :  Ibid,  78,  32  ;  Aguiar  : 
Ber.,  5,  370. 

20  grams  naphthalene. 

100  grams  nitric  acid   (sp.  gr.  1.33). 

55  cc.  nitric  acid  (sp.  gr.   1.42). 
25  cc.  water. 

Put  in  a  beaker  20  grams  of  naphthalene,  add  100  grams  (75 
cc.)  of  nitric  acid  (sp.  gr.  1.33)  and  allow  to  stand  for  several 
days.  Dilute  with  water,  filter,  wash  and  dry.  Moisten  with  a 
very  little  alcohol  and  treat  with  carbon  bisulphide,  which  dis- 
solves the  mononitro  compound.  Filter  from  the  insoluble  dinitro 
compound,  and  evaporate  the  solution  to  dryness.  (Beware  of 
flames.}  The  solution  can  be  evaporated  on  a  previously  heated 
water-bath  in  a  hood,  all  flames  in  the  neighborhood  being  extin- 
guished. Recrystallize  from  alcohol.  Yield  17  grams. 

a-Nitronaphthalene  crystallizes  in  fine  yellow  needles  which 
melt  at  61°.  It  boils  at  304°.  It  gives  by  oxidation  nitrophthal- 
ic  acid,  while  the  aminonaphthalene  obtained  by  its  reduction 
gives  by  oxidation  phthalic  acid. 

By  reduction  it  gives  a-naphthtylamine  which  is  used  for  the 
determination  of  nitrites  in  potable  waters. 

100.  Preparation  of  a  Nitro  Derivative  of  an  Amine  and  Elim- 

/CH3(i) 
ination  of  the  Amino  Group.  —  w-Nitrotoluene,   C6H4<( 

XN02  (3) 

Literature  —  Monnet,  Reverdin,  Nolting:  Ber.,  12,  443;  Nolting,  Witt: 
Ibid,  18,  1336  ;  Buchka  :  Ibid,  22,  829  ;  Noyes,  Moses  :  Am.  Chem.  J.,  7> 
149;  Noyes:  Ibid,  10,  475;  Schraube,  Romig:  Ber..  26,  579. 


NITRO    COMPOUNDS  213 

20  grams  paraacetotoluide. 

75  cc.  nitric  acid  (1.42). 

30  cc.  concentrated  sulphuric   acid. 

50  cc.  alcohol. 

10  grams  potassium  hydroxide. 

13  cc.  water. 

15  grams  nitrotoluidine. 

60  cc.  absolute  alcohol. 

12  cc.  concentrated  sulphuric  acid. 

8  grams  (9  cc.)  ethyl  nitrite. 

Prepare  acetotoluide  by  boiling  paratoluidine  with  twice  its 
weight  of  glacial  acetic  acid  for  two  hours  (see  acetanilide,  p. 
157),  pouring  into  cold  water,  filtering  off,  washing  and  drying. 
Add  20  grams  of  the  finely  powdered  substance  in  small  por- 
tions to  a  mixture  of  75  cc.  of  nitric  acid  with  30  cc.  of  con- 
centrated sulphuric  acid.  Stir  with  a  thermometer  during  the 
addition,  and  keep  the  temperature  between  30°  and  40°  by 
setting  the  beaker  in  cold  water.  When  all  has  been  added  al- 
low the  beaker  to  stand  for  fifteen  minutes  and  then  pour  the  mix- 
ture into  cold  water,  filter  off  the  nitroacetotoluide,  wash  and  suck 
and  press  as  dry  as  possible  on  a  plate.  Put  the  substance  in  a 
flask,  add  50  cc.  of  alcohol,  heat  nearly  to  boiling,  and  add  care- 
fully a  solution  of  10  grams  of  potassium  hydroxide  in  13  cc. 
of  water.  Heat  on  a  water-bath  for  twenty  minutes.  Cool 
thoroughly,  filter  off  the  nitrotoluidine  on  a  plate,  wash  with  alco- 
hol diluted  with  two  volumes  of  water,  and  dry  thoroughly. 

Put  15  grams  of  the  nitrotoluidine  in  a  300  cc.  flask  and  add 
a  warm  mixture  of  60  cc.  of  absolute  alcohol  with  12  cc  .of  con- 
centrated sulphuric  acid;  cool  thoroughly  and  add  slowly  with 
vigorous  shaking  and  cooling,  7.5  grams  of  ethyl  nitrite  (see  122, 
p.  250).  Allow  to  stand  a  few  minutes,  and  then  warm  on  the 
water-bath  till  the  evolution  of  nitrogen  ceases.  Cool,  precipitate 
the  nitrotoluene  by  adding  water,  siphon  off  or  decant  most  of  the 
aqueous  solution,  and  distil  the  nitrotoluene  which  remains,  in  a 
current  of  steam  (see  22,  p.  71).  A  small  amount  of  nitrotolu- 


214  ORGANIC    CHEMISTRY 

ene  may  be  obtained  by  extracting  the  alcoholic  mother-liquors 
with  ether,  but  in  most  cases  it  is  not  worth  while  to  do  that. 
Separate  the  nitrotoluene  from  the  water  of  the  distillate,  and  dry 
it  in  vacuo  over  sulphuric  acid.  Yield  8  to  10  grams. 

Instead  of  the  method  given  here,  Meyer  and  Jacobson  ad- 
vise in  their  text-book  (Vol.  II,  p.  158)  to  dissolve  the  nitroto- 
luidine  in  a  mixture  of  three  parts  of  alcohol  and  three  parts, 
by  weight,  of  concentrated  sulphuric  acid,  cool,  add  the  theoreti- 
cal amount  of  sodium  nitrite  dissolved  in  the  smallest  possible 
amount  of  water,  and  then  warm  on  the  water-bath  as  above. 
In  our  experience  the  yields  obtained  in  this  way  are  much  less. 

Instead  of  adding  ethyl  nitrite,  the  mixture  of  nitric  oxide 
and  nitrogen  peroxide  (usually  called  nitrous  anhydride),  ob- 
tained by  boiling  arsenious  oxide  with  nitric  acid  (sp.  gr.  1.30- 
1.35),  may  be  passed  into  the  acid  alcoholic  solution  till  it  smells 
strongly  of  the  nitrous  ester  after  standing  a  short  time,  or  ethyl 
nitrite  may  be  passed  in  as  it  is  generated  at  such  a  temperature 
as  to  assume  the  gaseous  form  (see  122,  p.  250). 

Paraacetotoluide  crystallizes  in  rhombic  needles  which  melt  at 
153°.  It  boils  at  307°. 

3~Nitro-4-acetotoluide  crystallizes  from  water  in  fine  yellow 
needles  which  melt  at  94°-95°. 

3-Nitro-4-toluidine  crystallizes  in  red  prisms,  wnich  melt  at 
Ii6°-ii7°.  It  is  volatile  with  water  vapor. 

Meta-nitrotoluene  melts  at  16°,  and  boils  at  23O°-23i°.  By 
the  chromic  acid  mixture  it  is  oxidized  to  meta-nitrobenzoic  acid. 
By  an  alkaline  solution  of  potassium  ferricyanide  it  is  much  less 
easily  oxidized  than  ortho-  or  paranitrotoluene. 

loi.  Preparation  of  a  Nitro  Derivative  of  an  Amine. — />-amino- 


(I) 

<?-nitrotoluene,   C6H3— NO2     (2)  . 
\NH2     (4) 

Literature — Beilstein,  Kuhlberg:  Ann.,  155,  23;  Nolting  and  Collin :  Ber., 
17*  263;  Noyes,  Moses:  Am.  Cheni.  J.,  7>  150. 


NITRO   COMPOUNDS  215 

10  grams  />-toluidine. 

100  grams  concentrated  sulphuric  acid.  (sp.  gr.    1.84). 

7.5  grams  nitric  acid   (sp.  gr.   1.48). 

30  grams  concentrated  sulphuric  acid. 

500  cc.  ice-water. 

400  grams  acid  sodium  carbonate. 

Dissolve  10  grams  of  paratoluidine  in  200  grams  (120  cc.)  of 
cold  concentrated  sulphuric  acid.  Cool  to  o°  with  a  freezing 
mixture  (the  most  convenient  is  snow  or  ice  and  concentrated 
commercial  sulphuric  acid,  snow  and  salt  is  a  little  cheaper), 
and  drop  in  slowly  a  mixture  of  7.5  grams  (5  cc.)  of  nitric 
acid  (sp.  gr.  1.48),-  with  30  grams  (17  cc.)  of  concentrated  sul- 
phuric acid,  stirring  and  keeping  the  temperature  below  5°. 
Allow  the  mixture  to  stand  for  half  an  hour,  and  pour  into  500 
cc.  of  ice-water,  keeping  the  temperature  below  25°.  Filter,  add 
looo  cc.  of  water  and  neutralize  with  baking  soda.  About  400 
grams  will  be  required.  Filter  off  and  wash  the  precipitated 
nitrotoluidine,  and  crystallize  from  dilute  alcohol.  Yield  about 
10  grams. 

.  In  this  nitration  the  large  amount  of  sulphuric  acid  forms  an 
acid  sulphate  with  the  toluidine,  and  appears  in  that  way  to  so 
change  the  character  of  the  amino  group  that  the  nitro  group 
enters  in  the  meta  position  wijth  regard  to  it.  Compare  the 
preceding  preparation. 

Orthonitroparatoluidine  crystallizes  from  water  in  broad,  yel- 
low, monociinic  needles,  which  melt  at  77.5°. 

102.  Preparation  of  a  Nitro  Derivative  of  an  Aromatic  Acid.— 

xCCXH     (i). 
Meta-nitro-benzoic  acid,  C5H4<^ 

XN02        (3). 

Literature — Mulder:  Ann.,  34>  297;  Gerland :  Ibid,  91,  186;  Griess:  Ber.. 
8,  526;  10,  1871;  Widmann:  Ann.  193,  202:  C.  Liebermann :  Ber.,  10, 
862;  Ernst:  Ztschr.  chem.,  1860,  477. 

25  grams  benzoic  acid. 

50  grams  potassium  nitrate. 

75  grams  absolute  sulphuric  acid    (monohydrate). 


2l6  ORGANIC    CHEMISTRY 

Warm  75  grams  of  absolute  sulphuric  acid1  to  70°  in  a  beaker, 
and  add,  in  small  portions,  a  powdered  mixture  of  25  grams  of 
benzoic  acid  and  50  grams  of  potassium  nitrate,  stirring  vig- 
orously and  keeping  the  temperature  at  So0 -go0.  When  all  has 
been  added,  and  the  nitrobenzoic  acid  has  separated  as  an  oily 
layer  on  the  surface  of  the  liquid,  pour  the  contents  of  the  beaker 
into  a  porcelain  dish,  and  allow  the  product  to  solidify.  Separate 
the  cake  of  nitro  acids  from  the  acid  potassium  sulphate.  Put 
the  nitro  acids  (about  75  per  cent,  of  meta,  22  per  cent,  of  the 
ortho,  and  2^  per  cent,  of  the  para  acids  are  present  in  the  mix- 
ture) in  a  beaker  with  100  cc.  of  water,  heat  till  the  acids  melt,  and 
stir  thoroughly.  Cool,  filter,  and  wash  with  cold  water.  Dis- 
solve the  acid,  in  300-400  cc.  of  hot  water,  and  add  a  clear  con- 
centrated solution  of  barium  hydroxide  (about  30  grams)  to 
alkaline  reaction.  Cool,  filter,  and  wash.  The  barium  salts  of 
the  ortho  and  para  acids  pass  into  the  filtrate,  while  a  part  of  the 
ortho  acid  remained  in  solution  on  treatment  with  water  before. 
The  pure  meta  acid  can  be  obtained  by  treating  the  barium  salt 
with  200  cc.  of  hot  water  and  some  sulphuric  acid,  filtering 
hot  from  the  barium  sulphate,  which  separates,  and  cooling  the 
filtrate. 

Meta-nitro-benzoic  acid  melts  at  141°- 142°.  It  dissolves  in 
10  parts  of  hot  water,  and  in  425  parts  of  water  at  16.5°.  It 
is  very  easily  soluble  in  alcohol  and  ether.  The  barium  salt  is 
soluble  in  19  parts  of  boiling  water,  and  in  265  parts  of  cold 
water. 

The  ortho  and  para  acids  may  also  be  separated  from  the 
mixture  obtained  by  the  nitration  of  benzoic  acid,  but  are  more 
readily  obtained  by  the  oxidation  of  the  nitro-toluenes.  (See 
51,  p.  126.) 

1  Absolute  sulphuric  acid,  called  technically  the  "monohydrate,"  can  be  purchased  or 
may  be  prepared  by  cooling  concentrated  sulphuric  acid  to  o°  or  below,  until  it  crystal- 
lizes and  pouring  off  the  liquid  portion,  the  crystals  consisting  of  absolute  sulphuric  acid, 
if  the  acid  is  sufficiently  strong.  The  crystallization  may  be  started  with  crystals  obtained 
by  cooling  a  mixture  of  ordinary  sulphuric  acid  with  the  fuming  acid. 


Chapter  XIII 


AMINES 

The  simplest  method  of  preparing  amines,  and  one  which  usually 
gives   pure  compounds,   consists   in   reducing  nitro   compounds. 
RNO2  +  6H  =  RNH2  +  2H2O. 

The  reducing  agents  generally  used  are  tin  and  hydrochloric 
acid,  iron  and  acetic  acid  (in  manufacture),  ammonium  sul- 
phide, and  stannous  chloride.  This  method  of  preparation  is 
general  with  aromatic  compounds,  but  is  not  often  used  for 
members  of  the  marsh  gas  series,  because  of  the  difficulty  of  ob- 
taining the  nitro  compounds  required. 

A  method  of  great  historical  importance  consists  in  treating 
halogen  derivatives  with  an  aqueous  solution  of  ammonia. 
RBr  +   NH3  =   RNH2HBr. 

The  ease  with  which  secondary  and  tertiary  amines,  and 
quaternary  ammonium  salts  are  formed  by  this  reaction  detracts 
from  its  usefulness,  as  the  resulting  mixtures  are  often  difficult 
of  separation.  (For  a  method  of  separation  see  pp.  160  and 
267.) 

To  overcome  the  difficulty  which  arises  from  the  formation  of 
secondary  and  tertiary  amines  when  halogen  compounds  are 
treated  with  ammonia,  Gabriel  has  used,  successfully,  potassium 
phthalimide.  When  this  is  heated  with  halogen  compounds  to 
[5O°-2OO°  in  sealed  tubes  or  open  vessels,  according  to  the  nature 
of  the  halogen  compound,  derivatives  of  the  phthalimide  are 
formed.  These  may  be  saponified  with  separation  of  the  chloride 
of  the  primary  amine  by  heating  in  sealed  tubes  at  200°,  with 
three  parts  of  fuming  hydrochloric  acid.  (Ber.,  20,  2224;  21, 
566.2669.), 

/CO,  /COv 

RC1  f  C6H4<         >NK  =  C.H4<         >NR  +  KC1. 

XCCK 


/COv  /COOH 

C6H4<         >NR  4-  2H,0  4   HC1  =  C.H4<  +  RNH2HC1. 

XCCK  XCOOH 


2l8  ORGANIC    CHEMISTRY 

Another  method  of  attaining  the  same  end,  which  seems  very 
general  in  its  application,  has  been  worked  out  by  Delepine 
(Compt.  rend.,  120,  501;  124,  292).  On  heating  hexamethylene 
amine  with  halogen  compounds  in  solution  in  chloroform,  double 
compounds  are  produced.  When  these  are  heated  gently  with 
alcohol  and  concentrated  hydrochloric  acid  they  are  decomposed 
with  the  formation  of  a  primary  amine  and  methylene-diethyl 
ether. 

C6H12N4  +  RC1  =  C6H12N4/ 

NCI 

/R 

C6H12N/       +  i2C2H60  +  3HC1  =  3NH4C1  + 
Cl 

)C2H6 


RNHHC1  +  6CH 

OC2H5 

The  method  has  been  successfully  used  for  the  preparation  of 
benzyl  amine  and  of  allyl  amine. 

A  very  useful  method  consists  in  the  reduction  of  oximes  and 
hydrazones. 

-n  T> 

'\C  =  NOH  +  4H  =      \CHNH,  +  H2O. 
R'/  R'/ 

R\  R\ 

>C  =  NNHC6H5  +  4H  =        >CHNH2  +  C6H5NH2. 

R'/  R'/ 

The  best  reducing  agent  for  the  oximes  appears  to  be  absolute 
alcohol  and  sodium.  The  same  method  may  also  be  applied  to 
hydrazones,  or  the  latter  may  be  reduced  by  zinc  dust  and  acetic 
acid  in  alcoholic  solutions. 

Nitriles  may  be  reduced  to  amines  by  absolute  alcohol  and  so- 
dium, and  in  some  cases,  also,  by  the  use  of  zinc  and  hydrochloric 
or  sulphuric  acid. 

R  _  c  =  N  +  4H  R— CH2NH2. 

When  acid  amides  are  treated  with  bromine  and  sodium  hy- 
droxide, or,  in  many  cases,  if  treated  with  an  alkaline  solution  of 


AMINES  219 

sodium  hypobromite,  they  are  converted  into  amines  with  loss  of 
carbon  dioxide. 

R— CONH2  +  NaOBr  +  2NaOH  ==  RNH2  -f  NaBr  -f 
H2O  +  Na2COs. 

The  most  plausible  explanation  of  this  reaction  appears  to  be 
that  given  by  Stieglitz,  based  on  the  work  of  Nef  (Am.  Chem. 
J->  18,  751). 

R— CONH2  -f  NaOBr  R— CO— NHBr  +  NaOH. 

R  —  C  —  O 

|      w    +  NaOH  ==  R  —  C  =  O  +  NaBr  +  H2O. 

N<Rr  ! 

-N  — 

R  —  C  =  O  C  =  O 

I  ii 

—  N  —  R  —  N 

RN  =  CO  +  H20  =  RNH2  +  CO2. 

» 

Lengfeldt,  Stieglitz,  and  Elizabeth  Jeffreys  have  shown  (Ber., 
30,  898;  see  also  Am.  Chem.  J.,  15,  215,  504;  16,  307;  19,  295) 
that  in  the  case  of  aliphatic  amides  of  high  molecular  weights, 
where  the  reaction  cannot  be  applied  in  its  usual  form  owing  to 
the  formation  of  nitriles,  the  urethane  can  be  obtained  by  dis- 
solving the  amide  (i  molecule)  in  3  parts  of  methyl  alcohol, 
adding  a  solution  of  sodium  (2  atoms)  in  25  parts  of  methyl 
alcohol,  and  dropping  bromine  (2  atoms)  into  the  solution. 
After  warming  for  ten  minutes  on  the  water-bath,  the  solution  is 
acidified  with  acetic  acid,  evaporated,  the  inorganic  salts  remov-  » 
ed  with  water  and  the  urethane  separated  from  unchanged  amide 
by  solution  in  warm  ligroin.  The  urethane  is  decomposed  by 
heating  with  concentrated  sulphuric  acid  at  no°-i2O°  for  an 
hour,  or,  better,  by  distilling  with  three  to  four  times  its  weight 
of  slaked  lime. 

RCONHBr  -f  NaOCH3  =  RNHCOOCH,  -f  NaBr. 

Urethane 

RNHCOOCH,  +  Ca(OH)2  =  RNH2  -f  CaCO3  -f  CH3OH. 
Aromatic  amines  may  sometimes  be  prepared  from  phenols  by 


22O  ORGANIC    CHEMISTRY 

heating  with  concentrated  ammonia  in  sealed  tubes  or  by  heating 
with  ammonia  and  zinc  or  calcium  chloride. 

ROH  +  NH3  =  RNH2  +  H2O. 

Dimethyl  and  diethyl  amine  can  be  prepared  with  advantage 
by  decomposing  />-nitrosodimethyl-  or  diethylaniline  with  caustic 
soda. 

/N(C,H6),  xONa 

.      C6H4<  -f  NaOH  -  C6H/  +  NH(C2H5)2. 

\NO  XNO 

Complex  amines  containing  chromophore  groups  and  of  im- 
portance as  dyes  may  be  prepared  by  a  great  variety  of  methods, 
especially  by  condensations,  of  which  the  preparation  of  mala- 
chite green  (p.  241)  is  an  illustration.  Heterocyclic  compounds 
in  which  the  nitrogen  atom  forms  a.  part  of  the  ring  and  in  which 
the  nitrogen  may  or  may  not  have  the  property  of  combining 
with  acids  to  form  salts  are  also  prepared  in  many  ways.  The 
preparation  of  pyridine,  piperidine,  £[uinoline,  p.  238),  indigo, 
(p-  235)>  and  collidine  dicarboxylic  acid  ester  are  typical  of 
many  similar  preparations. 

When  a  ketone  or  aldehyde  is  treated  with  a  concentrated  aque- 
ous solution  of  potassium  cyanide  and  ammonium  chloride  the 
hydrocyanic  acid  and  ammonia,  present  in  such  a  solution  by 
hydrolysis,  condense  with  the  ketone  or  aldehyde  to  form  an 
a-amino  nitrile.  (Zelinsky,  Stadnikoff.  Ber.,  39,  1/26). 

R,  R,         /NH, 

>CO  +  NH3  +  HCN  -        >  C  <  4   H2O. 

R/  R/       \CN 

The  nitrile  may  be  saponified  to  an  a-amino  acid  by  hydro- 
chloric acid. 

Rv         /NH.  Rx          xNH., 

>  C  <  +  HC1  +  2H80  =       >  C  <  +  NH4C1. 

R/        \CN  W        XCO2H 

103.  Tlie  Preparation  of  an  Amine  by  the  Reduction  of  a  Nitro 
Compound. — Aniline,  C6H5NHS. 

Literature. — Unverdorben :  Pogg.  Ann.,  8,  397;  Runge:  Pogg.  Ann., 
31,  65;  32>  331;  Fritsche:  Ann.,  36,  84;  39>  76;  Anderson:  Ibid,  70,  32; 
Hofmann :  Ibid,  55>  200;  53,  n;  Wohler :  Ibid,  102,  127;  Merz,  Weith : 


AMINES  221 

Ber.,  13*  1298;  Merz,  Miiller :  Ibid,  ig»  2916;  Reverdin,  Harpe :  Ibid,  22, 
1004. 

25  grams  nitrobenzene. 

45  grams  tin. 

100  cc.  commercial  hydrochloric  acid. 

Put  into  a  500  cc.  flask  25  grams  of  nitrobenzene  and  45  grams 
of  tin.  Add  about  10  cc.  of  commercial  hydrochloric  acid, 
(sp.  gr.  1.16),  and  shake  vigorously.  If  the  solution  becomes  so 
hot  as  to  boil,  cool  it  somewhat  by  dipping  the  flask  in  cold  water. 
When  the  reaction  moderates  add  10  cc.  more  of  the  acid,  and 
continue  in  the  same  manner  till  100  cc.  have  been  added 
Warm  on  the  water-bath  till  the  odor  of  nitrobenzene  disappears. 
Cool,  add,  with  further  cooling  if  necessary,  a  solution  of  75 
grams  of  caustic  soda  in  100  cc.  of  water,  and  distil  off  the  sepa- 
rated aniline  with  water  vapor,  distilling  about  100  cc.  after  the 
distillate  ceases  to  appear  turbid.  Add  to  the  distillate  20  to  30 
grams  of  salt  and  some  ether,  separate  the  ethereal  solution, 
dry  it  by  allowing  it  to  stand  for  some  time,  best  over  night,with 
some  powdered  caustic  potash,  ptfur  off  into  a  distilling  bulb, 
distil  the  ether  from  the  water-bath,  and  then  the  aniline  with  a 
free  flame.  Yield  15  to  17  grams. 

Aniline  is  a  colorless  oil  with  a  slightly  aromatic  odor.  It 
melts  at  — 8°,  boils  at  183.7°,  and  has  a  specific  gravity  of  1.036 
at  o°,  and  1.0276  at  11.6°.  Aniline  forms  salts  which  crystallize 
well,  but  these  react  acid  toward  test  papers.  Aniline  dissolves 
in  31  parts  of  water  at  12.5°.  The  hydrochloride  is  easily  soluble 
in  alcohol  and  in  water,  and  melts  at  192°.  It  is  less  easily  soluble 
in  hydrochloric  acid,  a  characteristic  which  may  be  used  with  ad- 
vantage in  the  crystallization  and  purification  of  many  of  the 
chlorides  of  organic  bases.  Aqueous  solutions  of  aniline  give 
a  violet  color  on  the  addition  of  a  few  drops  of  a  solution  of  cal- 
cium hypochlorite  (chloride  of  lime). 

104.  Preparation  of  a  Nitre-Ammo  Compound  by  the  Re- 
duction of  a  Dinitro  Compound. — /-amino-0-mtrotoluene, 
/CH3  (i) 

CKHS-NO,    (2)   . 

(4) 


222  ORGANIC   CHEMISTRY 

Literature — See  101,  p.  214;  also  Beilstein  and  Kuhlberg:  Ann.,  i55,  13 

15  grams  toluene. 

35  cc.  nitric  acid  (1.42). 

35  cc.  sulphuric  acid. 

75  cc.  sulphuric  acid. 

15  grams  dinitrotoluene. 
50  cc.  alcohol. 
8  cc.  ammonia.    (0.90). 
Hydrogen  sulphide. 

Put  15  grams  of  toluene  in  a  small  flask  and  add  in  small 
portions,  70  cc.  of  a  mixture  of  equal  volumes  of  concentrated 
sulphuric  and  concentrated  nitric  acids,  shaking  vigorously  and 
cooling  somewhat.  After  the  mixture  has  all  been  added  and  the 
reaction  moderates,  add  75  cc.  of  concentrated  sulphuric  acid, 
shake  vigorously,  heat  to  about  130°  and  keep  the  mixture  at  that 
temperature,  shaking  vigorously  for  about  15  minutes.  Allow 
to  cool,  pour  into  water,  filter,  wash,  and  crystallize  the  dinitro- 
toluene from  alcohol.  20  to  25  grams  of  pure  dinitrotoluene, 
melting  at  70.5°,  should  be  obtained. 

Put  15  grams  of  the  dinitrotoluene  in  a  flask,  add  50  cc  of 
alcohol  and  8  cc.  of  concentrated  ammonia  (0.90),  pass  in  a 
rapid  current  of  hydrogen  sulphide  nearly  to  saturation,  connect 
the  flask  with  a  reversed  condenser  or  condensing  tube,  and 
heat  on  a  water-bath  for  half  an  hour.  Cool,  saturate  again 
with  hydrogen  sulphide,  and  heat  as  before.  Filter  hot,  cool  the 
filtrate,  add  water,  and  filter  off  the  precipitated  nitrotoluidine 
after  standing  for  some  time.  Purify  by  dissolving  in  dilute 
hydrochoric  acid,  filtering,  and  precipitating  again  with  am- 
monia. Yield  about  10  grams. 

Orthonitroparatoluidine  crystallizes  from  water  in  broad  yel- 
low monoclinic  needles,  which  melt  at  77.5°.  It  is  difficultly  solu- 
ble in  water  and  carbon  bisulphide,  easily  soluble  in  alcohol  and 
acids. 


AMINES  223 

105.  Preparation    of    a    Diamino    Derivative    of    Benzene. — 

/NH,     (i) 

^-Phenylenediamine,    C6H4^  (/>-Diaminobenzene). 

XNH2     (4) 

Literature — Grethen  :   Ber.,  9,  775  ;  Beilstein,  Kurbatow  :  Ann.,  197,  83 ; 
Nolting,  Collins:   Ber.,   17,  262;   Hobrecker:   Ibid,  5,  920. 
20  grams  acetanilide. 
75  cc.  nitric  acid  (142). 
30  cc.  sulphuric  acid  (1.84). 

20  grams  nitroacetanilide. 

30  grams  tin. 

80  cc.  commercial  hydrochloric  acid. 

Hydrogen  sulphide. 
Lime. 

Prepare  />-nitroacetanilide  exactly  as  directed  for  nitroacet- 
toluide  (see  p.  213).  Put  in  a  flask  20  grams  of  nitroacetanil- 
ide and  30  grams  of  tin.  Add  10  cc.  of  concentrated  com- 
mercial hydrochloric  acid,  and  shake  till  the  reaction  begins  to 
moderate ;  add  more  of  the  acid  and  shake  as  before,  and  con- 
tinue till  80  cc.  of  acid  have  been  added.  Then  heat  on  the  water- 
bath  till  the  reaction  is  complete.  The  nitro  group  is  reduced 
and  the  acetyl  group  is  alsq  removed.  Dilute  with  three  or  four 
volumes  of  water,  pour  off  from  any  undissolved  tin,  precipitate 
the  tin  from  the  solution  with  hydrogen  sulphide,  and  filter  on  a 
Witt  Plate  or  Hirsch  funnel  (see  p.  120).  The  hydrogen  sulphide 
is  best  generated  in  a  two-liter  acid  bottle  from  considerably 
more  than  the  theoretical  amount  of  iron  sulphide,  which  is 
placed  in  the  bottle  with  1500  cc.  of  water.  Somewhat  more  than 
the  theoretical  amount  of  concentrated  commercial  sulphuric 
acid  is  then  added,  in  small  portions,  through  the  thistle  tube. 
The  gas  should  be  passed  through  a  washing  tube  or  wash-bottle 
containing  a  little  water.  After  the  operation  is  over,  the  gener- 
ator should  be  emptied  at  once,  as  the  ferrous  sulphate  would 
crystallize  on  standing.  If  any  unused  ferrous  sulphide  is  left  in 
the  bottle,  and  the  latter  is  filled  up  at  once  with  water  to  prevent 
its  oxidation,  it  can  be  saved  for  use  again. 


224  ORGANIC    CHEMISTRY 

Evaporate  the  filtrate  to  a  small  volume,  filter  again,  if  neces- 
sary, through  a  hardened  filter,  and  allow  the  chloride  of  the 
phenylenediamine  to  crystallize. 

To  prepare  the  free  amine,  mix  the  chloride  with  an  equal 
weight  of  quicklime,  and  distil  from  a  small  retort.  The  para- 
phenylenediamine  may  be  recrystallized  from  benzene.  Yield 
10  to  12  grams. 

Paradiaminobenzene  crystallizes  from  benzene  in  shining  leaf- 
lets, which  melt  at  140°  and  boil  at  260°.  It  is  moderately  soluble 
in  hot  water. 

Paranitroacetanilide  melts  at  207°. 

1 06.  Preparation  of  an  Amine  by  the  Decomposition  of  an  Alkyl 
Derivative  of  Aniline.— Diethylamine,  (C2H5)aNH. 

Literature.— Hofmann :  Ann.,  74,  128,  135;  Elsbach :  Ber.,  15,  690; 
Piutti:  Ann.,  227,  182;  Pictet :  Ber.,  20,  3422;  Schloemann :  Ibid,  26,  1020; 
Reynolds:  J.  Chem.  Soc.,  61,  457;  Kopp :  Ber.,  8,  621;  Lippmann  u. 
Fleissner:  Ibid,  16,  1422;  Hofmann:  Ann.,  73,  91;  Wallach :  Ibid,  214, 
275 ;  Reinhardt  and  Staedel :  Ber.,  16,  29 ;  Baeyer  and  Caro :  Ibid,  7> 
963. 

30  grams  aniline. 

45  grams  ethyl  bromide. 

20  grams  sodium  hydroxide. 
60  cc.  water. 

35  grams  ethyl  aniline. 
45  grams  ethyl   bromide. 

20  grams   sodium  hydroxide. 
60  cc.  water. 

30  grams  diethylaniline. 

150  cc.  water. 

120  cc.  concentrated  hydrochloric  acid   (1.19). 

loo  grams  ice. 

1 6  grams  sodium  nitrite. 
80  cc.  water. 

70  grams  sodium  hydroxide. 
210  cc.  water. 


225 

Put  in  a  small  flask  30  grams  of  aniline  and  45  grams  of  ethyl 
bromide,  and  heat  with  a  reversed  condenser  for  one  or  two 
hours,  or  until  the  mass  solidifies.  Cool,  add  60  cc.  of  a  solution 
of  sodium  hydroxide  (3  cc.  —  I  gram),  with  cooling,  separate 
the  ethyl  aniline,  add  to  it  45  grams  of  ethyl  bromide,  and  heat 
with  reversed  condenser  as  before,  till  the  mass  solidifies.  Dis- 
solve in  water,  boil  to  expel  any  ethyl  bromide  which  remains, 
cool,  add  60  cc.  of  caustic  soda,  and  separate  the  diethyl  aniline. 
Dry  with  powdered  potassium  hydroxide,  and  distil,  collecting 
as  much  as  possible  of  the  portion  boiling  at  212°  -2  15°.  (Ani- 
line boils  at  183.7°,  ethyl  aniline  at  206°,  and  diethyl  aniline  at 

213.5°.) 

Dissolve  30  grams  of  the  diethyl  aniline  in  120*  cc.  of  concen- 
trated hydrochloric  acid  and  150  cc.  of  water,  cool,  add  100 
grams  of  ice,  and  when  the  solution  is  near  o°  add  slowly,  with 
stirring,  16  grams  of  sodium  nitrite  dissolved  in  80  cc.  of  water. 
After  an  hour  transfer  the  solution  of  nitrosodiethyl  aniline, 

/NO 
C6HX  ,  to  a  liter  flask  and  add  carefully,  with  shaking, 


210  cc.  of  a  strong  solution  of  sodium  hydroxide,  connect  with 
a  condenser  by  means  of  a  bent  tube,  and  distil,  collecting  the 
distillate  in  a  flask  containing  20  cc.  of  concentrated  hydrochloric 
acid.  The  solution  remaining  in  the  flask  may  be  used  for  the 
preparation  of  paranitrosophenol. 

The  hydrochloric  acid  solution  will  contain  diethylammonium 
chloride,  some  ethyl  aniline  regenerated  from  nitrosoethyl  aniline 
which  has  distilled  over,  some  .diethyl  aniline,  and  probably  other 
substances.  Evaporate  on  the  water-bath  to  about  50  cc.,  trans- 
fer to  a  200  cc.  flask,  cool  thoroughly,  add,  with  cooling,  60  cc.  of 
sodium  hydroxide  (3  cc.  =  I  gram),  connect  the  flask  by  means 
of  a  tightly  fitting  cork,  with  a  glass  tube  one  cm.  in  diameter 
and  about  60  cm.  long,  and  held  in  a  clamp  at  an  angle  of  45° 
with  the  perpendicular.  About  15  cm.  of  the  upper  end  of  the 
tube,  which  serves  as  a  reflex  condenser,  should  be  bent  down- 
ward and  this  should  dip  into  a  flask  containing  10  cc.  of  con- 
centrated hydrochloric  acid.  If  the  lower  portion  of  the  tube 
15 


226  ORGANIC    CHEMISTRY 

is  filled  with  glass  beads  a  better  separation  will  be  effected.  Dis- 
til very  slowly,  in  such  a  manner  that  the  ethyl  aniline  and  simi- 
lar substances  almost  entirely  condense  and  run  back.  Sometimes 
it  may  be  necessary  to  neutralize  the  distillate  with  50  cc.  of 
sodium  hydroxide,  and  distil  again  before  a  pure  distillate  can  be 
obtained.  Finally  evaporate  the  solution  of  diethylammonium 
chloride  nearly  or  quite  to  dryness,  transfer  to  a  flask  or  distilling 
bulb,  decompose  with  a  very  concentrated  solution  of  sodium  or 
potassium  hydroxide,  and  distil  from  the  water-bath.  To  obtain 
the  amine  free  from  water  it  must  be  dried  with  fused  caustic 
potash  and  distilled  again.  Yield  7  to  8  grams.  ^ 

Diethyl  amine  boils  at  55°-56°,  and  has  a  specific  gravity  of 
0.7028  at  25°.  The  hydrochloride  melts  at  2i5°-2i7°,  boils  at 
32o°-33O°,  and  is  very  easily  soluble  in  water,  but  difficultly  solu- 
ble in  absolute  alcohol. 

107.  Preparation  of  an    Amine    from    an    Oxime.  —  Isopropyl 


3X      ,2 
amine,  x^x  •     (2-atninopropane.) 


Literature  —  Sierch:  Ann.,  148,  263;  Gautier:  Ann.  chim.  phys.,  [4], 
17,  251;  Hofmann:  Ber.,  15,  768;  Taf  el  :  Ibid,  19,  1926;  Goldschmidt:  Ibid, 
20,  728;  Noyes:  Am.  Chem.  J.,  i4i  226;  15,  540. 

10  grams  acetoxime. 

20  grams  sodium. 

240  cc.  absolute  alcohol. 

Put  in  a  200  cc.  round-bottomed  flask  20  grams  of  sodium, 
connect  with  a  long,  reversed  condenser,  and  pour  through  the 
latter  a  solution  of  10  grams  of  acetoxime  in  60  cc.  of  absolute 
alcohol.  By  means  of  a  short  tube,  bent  twice  at  right  angles 
and  passing  through  rubber  stoppers,  connect  the  top  of  the 
condenser  with  a  U-tube  containing  5  to  6  cc.  of  concentrated 
hydrochloric  acid.  Because  of  the  low  boiling-point  of  iso- 
propyl  amine  this  is  necessary,  but  with  amines  of  higher  molecu- 
lar weight  it  is  not  required.  When  the  first  violent  action 
slackens,  warm  on  an  asbestos  plate  and  add  from  time  to  time 
through  the  condenser,  more  alcohol,  whenever  a  crust  forms 
on  the  sodium.  About  240  cc.  of  alcohol  will  be  required.  When 


AMINES  227 

the  sodium  has  all  dissolved,  add  40  cc.  of  water  through  the 
condenser,  cool,  and  then  distil  off  the  alcohol  and  isopropyl 
amine,  collecting  in  a  flask  containing  12  cc.  of  concentrated  hy- 
drochloric acid,  including  that  from  the  U-tube.  Evaporate  to  dry- 
ness,  and  preserve  the  amine  in  the  form  of  its  hydrochloride. 
Yield  8  to  10  grams. 

Isopropyl  amine  boils  at  31.5°,  and  has  an  ammoniacal,  fishy 
odor.  Its  specific  gravity  is  0.690  at  18°.  The  hydrochloride  is  del- 
iquescent and  melts  at  i53°-i55cf.  The  chloroplatinate  is  diffi- 
cultly soluble,  and  melts  at  227°-228°.  The  salt  is  easily  pre- 
pared by  adding  chloroplatinic  acid,  ("platinic  chloride"), 
H,PtCl6,  to  a  concentrated  solution  of  the  chloride.  It  can  be 
analyzed  by  careful  ignition  in  a  porcelain  crucible. 

108.  Preparation  of  an  Amine  by  the  Reduction  of  a  Cyanide.— 
o>-Phenyl-ethyl-amine,  C6H5CH,CH2NH2.  ( il-amino-ethylphen.) 

Literature — Cannizzaro:  Ann.,  96,  247;  Mann:  Ber.,  14,  1645;  Stadel: 
Ibid,  19,  1951 ;  Hotter :  Ibid,  20,  82 ;  Spica,  Columbo :  Gaz.  chim.  ItaL, 
5.  124;  Bernthsen:  Ann.,  184,  304;  Ladenburg:  Ber.,  18,  2956;  8,  i9i  782; 
Hofmann:  Ibid,  18,  2740;  Hoogewerf,  van  Dorp:  Rec.  trav.  chim.  Pays- 
Bas.,  5>  254;  Filed,  Piccini:  Ber.,  12,  1700. 

30  grams  benzyl  chloride. 
38  cc.  alcohol. 

18  grams  potassium  cyanide. 
17  grams  water. 


5  grams  benzyl  cyanide. 

6  grams  sodium. 

70  cc.  absolute  alcohol. 


8  cc.  hydrochloric  acid   (sp.  gr.  i.io). 

Put  in  a  round-bottomed  flask  18  grams  of  pure  powdered 
potassium  cyanide,  17  cc.  of  water,  30  grams  of  benzyl  chloride, 
and  38  cc.  of  alcohol.  Connect  with  an  upright  condenser,  and 
boil  on  a  wire  gauze  or  asbestos  plate  for  3  to  4  hours.  By 
means  of  a  separatory  funnel  separate  the  alcoholic  solution, 
containing  the  benzyl  cyanide,  from  the  lower  aqueous  layer  and 
distil  the  former.  The  alcohol  and  water  may  be  distilled  with 
advantage  from  a  water-bath  under  diminished  pressure  and  the 


228  ORGANIC   CHEMISTRY 

heating  continued  till  the  residual  liquid  is  dry  (see  55,  p.  138). 
In  any  case  the  portion  boiling  at  2io°-24O°  will,  if  dry,  be 
sufficiently  pure  for  this  preparation.  Yield  of  benzyl  cyanide 
20  to  22  grams. 

Put  in  a  200  cc.  round-bottomed  flask  6  grams  of  sodium,  cut 
in  small  pieces,  add  a  warm  solution  of  5  grams  of  benzyl  cy- 
anide in  30  cc.  of  absolute  alcohol,  connect  with  an  upright  con- 
denser, and  heat  rapidly  to  boiling.  Continue  to  boil  and  add 
more  alcohol  as  necessary,  in  all  70  to  80  cc.,  till  the  sodium  is 
dissolved.  Distil  off  the  alcohol  and  the  phenylethylamine  in  a 
current  of  steam,  distilling  as  long  as  the  distillate  comes  over 
alkaline.  Add  to  the  distillate  8  cc.  of  hydrochloric  acid,  evapo- 
rate to  a  small  volume,  filter,  and  evaporate  to  dryness.  Transfer 
the  residue  to  a  small  test-tube,  dissolve  in  2  to  3  cc.  of  hot  water, 
cool,  add  8  cc.  of  sodium  hydroxide  (3  cc.  =  i  gram),  and  a 
few  cc.  of  ether,  and  shake  vigorously.  Allow  the  ethereal 
layer  to  separate,  and  by  means  of  a  pipette  with  a  fine  capillary 
tube,  remove  as  much  as  possible  of  the  aqueous  solution  from 
below.  Pour  off  the  ethereal  solution  into  a  dry  tube,  rinse  with 
a  little  ether,  and  dry  the  ethereal  solution  by  adding  solid  caustic 
potash  and  leaving  it  for  24  hours.  Transfer  to  a  small  (15  cc. 
or  less)  distilling  bulb,  and  distil  the  ether  through  a  condenser 
and  then  the  amine  directly  into  a  small  preparation  tube.  Yield 
about  2.5  grams  of  the  hydrochloride,  and  1.5  grams  of  the  dis- 
tilled amine. 

This  method  of  reducing  cyanides'  led  Ladenburg  to  the  syn- 
thesis of  cadaverine  from  trimethylene  cyanide, 

CNCH2CH2CH2CN. 
With  ethylene  cyanide  and  phenyl  cyanide  it  gives  less  satisfac- 
tory results,  owing,  in  the  latter  case,  to  secondary  reactions 
which  give  partly  benzene  and  sodium  cyanide  and  partly  so- 
dium benzoate  and  ammonia. 

Benzyl  cyanide  boils  at  231.7°.  o>-Phenyl-ethylamine  is  a  col- 
orless liquid  which  has  a  slightly  ammoniacal  odor,  and  boils  at 
198°.  It  has  a  specific  gravity  of  0.958  at  24.4°.  It  is  a  strong  base. 
It  is  somewhat  soluble  in  water,  and  is  easily  soluble  in  alcohol 


AMINES  229 

and  ether.  The  hydrochloride,  C6H5CH2CH2NH2HC1,  crystal- 
lizes from  absolute  alcohol  in  leaflets  or  plates,  which  melt  at  217°  • 
and  dissolve  in  il/4  parts  of  water  at  14°.  It  is  less  easily  solu- 
ble in  hydrochloric  acid,  easily  soluble  in  alcohol.  The  chloro- 
platinate  is  difficultly  soluble  in  cold  water. 

109.  Benzyl  Amine. — C6H5CH,2NH2,  Aminomethylphen. 

Literature— Mendius :  Ann.,  121,  144;  Bamberger,  Ladter:  Ber.,  20, 
1709;  Cannizzaro:  Ann.,  i34»  128;  Hof  mann :  Ber.,  18,  2738;  Taf  el :  Ibid, 
iQi  1928;  Curtius,  Lederer:  Ibid,  19,  2463;  Leuckhart,  Bach:  Ibid,  19* 
2128;  Goldschmidt :  Ibid,  19,  3232;  Mason:  J.  Chem.  Soc.,  63,  1313; 
Seelig:  Ber.,- 23,  2971;  Hoogewerf,  van  Dorp:  Rec.  trav.  chim.  Pays-Bas., 
5.  253 ;  Delepine :  Compt.  rend.,  120,  501 ;  124,  292. 

50  cc.  formaldehyde  solution  (40  per  cent. ). 
50  cc.  ammonia   (sp.  gr.  0.90). 

10  grams  hexamethylene  amine. 
10  grams  benzyl  chloride. 
30  cc.  chloroform. 

1 6   grams    double    compound    of    hexamethylene    amine    with 
benzyl  chloride. 
45  cc.  alcohol. 
15  cc.  concentrated  hydrochloric  acid. 

Put  in  a  150  cc.  distilling  bulb  50  cc.  of  a  40  per  cent,  solu- 
tion of  formaldehyde  and  add  in  small  portions,  cooling  some- 
what, 50  cc.  of  ammonium  hydroxide  (0.90).  Heat  for  5  to  10 
minutes  on  a  water-bath,  put  in  the  mouth  of  the  bulb  a  rubber 
stopper  bearing  a  fine  capillary  tube  (see  75,  p.  171),  and  distil 
as  rapidly  as  possible  from  the  water-bath,  under  diminished 
pressure,  till  the  residue  of  hexamethylene  amine  appears  dry. 
Rinse  out  the  amine  with  a  mixture  of  two  volumes  of  ether 
with  one  volume  of  ajcohol  and  suck  off  on  a  Witt  plate.  Wash 
with  a  little  ether  and  dry  on  the  water-bath.  10  grams  of  the 
amine  should  be  obtained.  A  small  additional  quantity  of  amine 
may  be  obtained  from  the  alcohol-ether  mother-liquors. 

Put  in  a  small  flask  10  grams  of  the  hexamethylene  amine,  30 
cc.  of  chloroform,  and  10  grams  of  benzyl  chloride.  Connect 
with  an  upright  condenser,  and  boil  gently  on  a  water-bath  for 


230  ORGANIC   CHEMISTRY 


half  an  hour.  Allow  to  cool,  filter,  and  wash  with  a  little 
chloroform.  About  16  grams  of  the  double  compound, 

/CH2C6H5 

C6H12N4<^  ,    should  be  obtained.     An  additional  small 

\C1 

amount  of  the  compound  will  separate  from  the  mother-liquors 
on  standing. 

Put  in  a  distilling  bulb  16  grams  of  the  double  compound,  last 
mentioned,  and  60  cc.  of  a  mixture  of  three  volumes  of  alcohol 
and  one  volume  of  concentrated  hydrochloric  acid.  Connect  with 
an  upright  condenser,  and  heat  on  a  water-bath  for  an  hour, 
then  distil  from  the  water-  bath  the  methylenediethyl  ether, 

/OC2H5 

CH2<f  ,  which  has  been  formed.  Add  to  the  residue  20  cc.  of 

XOC2H5 

the  same  mixture  of  alcohol  and  hydrochloric  acid,  and  heat  again 
for  an  hour  on  the  water-bath,  allowing  the  methylenediethyl  ether 
to  distil  through  a  condenser  as  it  is  formed.  Then  distil  over  a 
free  flame  till  20  to  25  cc.  in  all  have  passed  over.  Repeat  this 
process  a  second  time,  and,  if  necessary,  a  third,  or  till  the  odor 
of  the  ether  can  no  longer  be  detected  in  the  distillate.  The 
complete  decomposition  of  the  double  compound  is  essential  to 
the  success  of  the  preparation. 

Transfer  the  residue  in  the  bulb  to  an  evaporating  dish,  and 
evaporate  on  the  water-bath  nearly  or  quite  to  dryness.  Trans- 
fer the  residue  to  a  flask,  add  a  strong  solution  of  sodium  hy- 
droxide in  considerable  excess,  separate  the  benzyl  amine  by 
means  of  a  separatory  funnel,  dry  it  by  allowing  it  to  stand  with 
solid  caustic  potash,  and  distil.  Yield  4  to  5  grams.  In  work- 
ing with  larger  quantities  the  yield  is  somewhat  "better. 

The  methylenediethyl  ether,  which  is  formed  as  a  by-product, 
boils  at  89°,  and  has  a  specific  gravity  of  0.851  at  o°.  It  dis- 
solves in  ii  volumes  of  water  at  18°. 

Benzyl   amine   boils   at    183°,   and  has   a   specific   gravity   of 

18  o° 

0.9826   at  —  '-£-  .     It  is  miscible  in  all  proportions  with  water, 
4 

alcohol,  and  ether,  but  is  separated  from  aqueous  solutions  on  the 


AMINES  231 

addition  of  sodium  hydroxide.     It  has  a  strong  alkaline  reaction, 
and  absorbs  carbon  dioxide  from  the  air. 

no.  Preparation  of  an  Amino  Acid  from  a  Halogen  Derivative 


of  an  Acid.  —  Glycocoll,  CH  /  .     (Aminoethanoic  acid.) 

\CO.H 

Literature  —  Bracormot.  Ann.  chim.  phys.,  1820,  i3»  114;  Perkin,  Duppa: 
Ann.,  108,  112;  Heintz  :  Ibid,  122,  257;  124,  297;  v.  Nencki  :  Ber.,  16,  2827; 
Kraut:  Ann.,  266,  295;  Ber.,  23,  2577;  Gabriel,  Kroseberg:  Ibid,  22,  427. 

25  grams  monochloracetic  acid. 

25  cc.*  water. 

300  cc.  ammonium  hydroxide   (sp.  gr.  0.90). 

To  300  cc.  of  ammonia  (0.90)  hi  a  liter  flask  or  distilling  bulb, 
add  a  solution  of  25  grams  of  monochloracetic  acid  in  25  cc.  of 
water.  After  thorough  shaking,  allow  the  whole  to  stand  for  24 
hours.  Distil  off  most  of  the  excess  of  ammonia  with  water 
vapor  (see  22,  p.  71),  and  evaporate  the  solution  on  the  water- 
bath  till  the  odor  of  ammonia  is  no  longer  apparent.  Add  to  the 
solution  the  copper  oxide  prepared  from  35  grams  of  copper  sul- 
phate by  precipitating  from  a  hot  solution  with  sodium  hydroxide, 
and  washing  twice  by  decantation.  Boil,  filter,  evaporate,  and 
crystallize  the  copper  aminoacetate  which  is  formed. 

To  prepare  the  free  glycocoll,  dissolve  the  copper  salt  in  water, 
add  a  little  freshly  precipitated  'and  slightly  washed  aluminium 
hydroxide,  precipitate  with  hydrogen  sulphide,  boil  a  few  min- 
utes, filter,  and  wash  with  water  containing  a  little  hydrogen 
sulphide.  Evaporate  the  filtrate  to  a  small  volume  and  allow  the 
glycocoll  to  crystallize. 

In  case  the  glycocoll  contains  an  ammonium  compound,  warm 
the  concentrated  solution  with  milk  of  lime  until  the  odor  of  am- 
monia disappears,  filter,  precipitate  the  calcium  with  ammonium 
carbonate,  filter,  and  crystallize. 

The  addition  of  the  aluminium  hydroxide  prevents  the  forma- 
tion of  a  colloidal  solution  of  the  copper  sulphide  which  is 
difficult  to  filter. 

Yield   5   to   8  grams.     The  yield   is  very  considerably  below 


232  ORGANIC   CHEMISTRY 

' 

the  theoretical,  because  of  the  formation  of  the  secondary  and 
tertiary  amino  acetic  acid,  NH(CH2CO,H)2  and  N(CH2CO2H)3. 
The  large  excess  of  ammonia,  and  the  quick  mixing  of  the 
chloracetic  acid  with  the  ammonia,  after  it  has  been  added, 
tend  to  increase  the  amount  of  the  primary  compound,  which 
is  desired. 

Glycocoll  crystallizes  in  monoclinic  crystals,  which  turn  brown' 
at  228°,  and  melt  at  232° -236°.  It  is  soluble  in  4.3  parts  of  cold 
water,  in  930  parts  of  alcohol  of  0.828  sp.  gr.,  and  insoluble  in 
absolute  alcohol.  Its  neutral  solution  gives  a  deep  red  color  with 
ferric  chloride.  It  forms  crystalline  salts  with  nitric  and  with 
hydrochloric  acid.  When  distilled  with  barium  hydroxide  it 
gives  methyl  amine  and  barium  carbonate.  With  nitrous  acid 

/CO.H 

it  gives  glycollic  acid,   CtT/ 

X)H 

in.  Preparation  of  an  Acyl  Derivative  of  an  Amino  Acid. — 
Hippuric  acid,  C6H5CONHCH12CO2H.  (Benzoyl  aminoacetic 
acid). 

Literature. — Occurrence  in  urine  of  cattle,  Kraut:  Jahresb.,  1858,  573; 
Henneberg,  Stohmann  and  Rautenberg :  Ann.,  124?  200 ;  In  human  urine. 
Hallwachs:  Ann.,  106,  164;  In  urine  of  persons  who  have  taken  benzoic 
acid,  Herter;  Report  on  use  of  benzoic  acid  as  a  preservative,  C.  A., 
I9I°>  2690;  Preparation,  Baum :  Ber.,  19,  502;  From  urine  of  the  horse 
or  cow,  Gregory:  Ann.,  63,  125. 

2.5  grams  aminoacetic  acid. 

30  cc.  sodium  hydroxide  (10  per  cent.). 

4.5  grams  benzoyl  chloride. 

Dissolve  2.5  grams  (1/30  mol.)  of  glycocoll1  in  30  cc.  of  a 
ten  per  cent,  solution  of  sodium  hydroxide,  add  4.5  grams  (1/30 
mol.)  of  benzoyl  chloride  and  shake  till  the  odor  of  the  chloride 
disappears.  Filter,  if  the  solution  is  not  clear,  and  precipitate 
the  hippuric  acid  with  a  slight  excess  of  hydrochloric  acid. 
Recrystallize  from  hot  water. 

1  Instead  of  free  glycocoll  the  necessary  amount  of  the  copper  salt  may  be  dis- 
solved in  water  and  the  copper  precipitated  as  directed  oil  p.  231.  The  filtrate  from  the 
copper  sulphide  may  then  be  evaporated  to  a  small  volume  and  the  solution  used  as 
directed. 


AMINES  233 

Hippuric  acid  crystallizes  in  thick  needles  which  melt  at  187.5°. 

The  preparation  of  hippu'ric  acid  here  given  is  closely  related 
to  the  preparation  of  polypeptides  by  Fischer  and  the  formation 
of  hippuric  acid  in  the  animal  organism  is  very  probably  re- 
lated to  the  synthesis  of  proteins  in  the  processes  of  life. 

112.  Preparation  of  an  a-Amino  Acid  Through  the  Amino- 
nitrile.— a-Aminoisobutyric  acid,  (CH8)aCHNH2CO2H. 

Literature — Urech :  Ann.,  164,  268 ;  Tiemann,  Friedlander :  Ber..  14* 
1971;  Zelinsky,  Stadnikoff :  Ber.,  39»  1/26. 

13  grams  potassium  cyanide. 
10.6  grams  ammonium  chloride. 
Water  to  dissolve  each. 

1 1. 6  grams   acetone. 
Concentrated  hydrochloric  acid. 

Dissolve  separately  13  grams  (^5  mol.)  potassium  cyanide 
and  10.6  grams  (j/s  mol.)  of  ammonium  chloride  in  two  small 
flasks.  Put  the  solution  of  ammonium  chloride  into  a  100  cc. 
strong,  glass  stoppered  bottle,  add  n.6  grams  (l/s  mol.)  of  ace- 
tone, then  the  solution  of  potassium  cyanide,  insert  the  stopper, 
mix  quickly  and  tie  the  stopper  down  by  means  of  a  piece  of 
cloth  placed  over  the  top  and  tied  tightly  around  the  neck  of  the 
bottle.  Allow  the  mixture  to  stand  in  a  warm  place  (4O°-5O°) 
over  night.  Transfer  the  solution  to  a  strong,  round-bottomed 
flask  and  add  (under  the  hood}  an  equal  volume  of  concentrated 
hydrochloric  acid.  Connect  with  an  upright  condenser  and  boil 
for  two  hours.  Pour  the  solution  into  an  evaporating  dish  and 
evaporate  to  dryness  either  on  the  water-bath  or  on  an  asbestos 
plate,  but  in  the  latter  case  care  must  be  taken  that  the  residue 
is  not  overheated.  Transfer  the  residue  to  a  flask  and  extract 
it  repeatedly  with  a  mixture  of  10  parts  of  alcohol  with  one  of 
ether,  which  will  dissolve  the  hydrochloride  of  the  amino  acid 
but  will  leave  the  inorganic  salts  undissolved. 

Distil  off  the  alcohol  and  ether,  dissolve  the  hydrochloride 
of  the  amino  acid  in  a  small  amount  of  water,  add  twice  the 
theoretical  amount  of  lead  carbonate  and  warm  on  the  water- 


234  ORGANIC   CHEMISTRY 

bath  till  effervescence  ceases.  Cool  thoroughly,  filter  on  a  plate 
and  suck  as  dry  as  possible,  moisten  once  with  a  very  little  water 
and  suck  off  again.  Remove  the  lead  contained  in  the  nitrate 
by  means  of  hydrogen  sulphide,  and  evaporate  the  filtrate  till 
the  amino  acid  crystallizes.  Yield  15  grams. 

a-Aminoisobutyric  acid  crystallizes  in  plates  which  sublime  at 
28o°-28i°  without  melting.     It  is  very  easily  soluble  in  water/' 
difficultly  soluble  in  alcohol,  insoluble  in  ether. 

113.  Preparation  of  an  Amino  Acid  from  the  Half  Amide  of  a 

/CO,H  (i) 
Bibasic    Acid. — Anthranilic    acid,    C6HX  (2-Amino- 

XNH2     (2) 
benzoic  acid). 

Literature — Laurent :  Jahresb.,  1847-48,  589 ;  Ann.,  39,  91 ;  Kuhara : 
Am.  Chem.  J.,  3,  29;  Aschan :  Be.r.,ig,  1402;  Fritzsche :  Ann.,  39i  83; 
Beilstein,  Kuhlberg:  Ibid,  163,  138;  Bedson :  J.  Chem.  Soc.,  37,  752, 
(1880)  ;  Hoogewerf,  van  Dorp:  Rec.  trav.  chim.  Pays-Bas.,  10,  6,  Marig- 
nac:  Ann.,  42,  215. 

20  grams  phthalic  anhydride. 
80  cc.  ammonia   (0.96). 

64  cc.  hydrochloric  acid   (1.112). 

16.5  grams  phthalamidic  acid. 

100  cc.  sodium  hydroxide,  (10  per  cent.). 

140  cc.  sodium  hydroxide   (10  per  cent.). 
1 6  grams  bromine  (5.1  cc.). 

35  cc.  hydrochloric  acid  (1.112). 
40  cc.  acetic  acid  (30  per  cent.). 

Add  20  grams  of  finely  powdered  phthalic  anhydride  in  por- 
tions to  80  cc.  of  ammonia  (sp.  gr.  0.96 — not  stronger — as  strong 
ammonia  may  cause  the  formation  of  phthalimide)  in  a  200  cc. 
flask,  shaking  and  cooling  the  mixture.  When  the  anhydride  is 
nearly  dissolved  filter  and  to  the  filtrate  add  64  cc.  of  hydro- 
chloric acid  (4  cc.  =  i  gram),  cool  again  thoroughly  with  shak- 
ing, filter  off  on  a  plate,  stop  the  pump>  moisten  with  water,  suck 


AMINES  235 


off  and  repeat  once.     Dry  the  phthalamidic  acid,  C6H/^  , 

\CONH2 

on  filter-paper  in  the  air,  or,  better,  in  vacua  over  sulphuric  acid.- 
The  yield  should  be  about  20  grams. 

Put  140  cc.  of  a  ten  per  cent,  solution  of  sodium  hydroxide 
in  a  flask,  add  from  a  burette  16  grams  (5.1  cc  =  I  mol.)  of 
bromine,  and  dissolve  it  immediately  by  giving  the  flask  a  quick 
rotary  motion.1  Dissolve  16.5  grams  (i  mol.)  of  phthalamidic 
acid  in  100  cc.  of  ten  per  cent,  sodium  hydroxide,  and  add  the 
solution  of  sodium  hypobromite  in  portions  of  about  20  cc.  at 
intervals  of  one  to  two  minutes,  cooling  after  each  addition. 
Neither  solution  should  stand  but  a  few  minutes  before  use. 
Allow  the  mixture  to  stand  for  half  an  hour,  add  a  little  of  a 
strong  solution  of  acid  sodium  sulphite  to  reduce  the  excess  of 
sodium  hypobromite,  and  35  cc.  of  hydrochloric  acid  (4  cc.  = 
I  gram),  carefully,  on  account  of  the  effervescence.  Evapo- 
rate to  about  100  cc.  Filter,  if  necessary  and  add  40  cc.  of 
acetic  acid  (30  per  cent.).  Filter  off  the  anthranilic  acid  after 
cooling,  suck  it  as  free  as  possible  of  the  mother-liquors  and 
recrystallize  from  hot  water.  Yield  10  to  n  grams. 

For  a  discussion  of  the  reactions  involved  in  the  transforma- 
tion of  the  amide  group  into  an  amino  group  with  loss  of  car- 
bonyl  see  p.  219. 

Anthranilic  acid  crystallizes  in  leaflets  which  melt  at  144°- 
145°.  It  is  easily  soluble  in  water.  The  aqueous  solution  shows 
a  blue  fluorescence  and  tastes  sweet. 

The  preparation  of  anthranilic  acid  from  indigo  is  of  especial 
historic  interest.  The  acid  may  also  be  prepared  by  the  reduc- 
tion of  orthonitrobenzoic  acid. 

114.  Preparation  of  Indigo  from  Anthranilic  Acid, 

/CO  v  /CO  v 

C.H4<         >C:C/         >C6H, 
/          \/ 


1  A  hypobromite  solution  more  nearly  free  from  bromate  may  be  prepared  by  putting 
the  bromine  in  a  glass-stoppered  wash-bottle,  set  in  warm  water  and  aspirating  the  vapor 
of  the  bromine  into  the  solution  of  sodium  hydroxide  contained  in  two  wash-bottles  set 
in  cold  water. 


236  ORGANIC   CHEMISTRY 

Literature — Baeyer's  synthesis  of  indigo:  Ber.,  n,  1228,  1296;  13* 
2254 ;  Heumann's  synthesis :  Ber.,  23,  3431 ;  Mauthner  and  Suida :  Mon- 
atsh,  9,  728;  History  of  the  synthesis  of  indigo,  Baeyer:  Ber.,  33>  LI; 
Brunck:  Ber.,  33,  LXXI ;  Henle :  Anleit.  zur  org.  prap.  Prakticum,  p.  63. 

6.8  grams  anthranilic  acid. 
5.7  grams  chloracetic  acid. 
8.5  grams  dry  sodium  carbonate. 
50  cc.  water. 

•  Hydrochloric  acid. 

4  grams  phenylglycine-0-carboxylic  acid. 
17  cc.  sodium  hydroxide   (10  per  cent). 

10  grams  sodium  hydroxide. 
10  grams  potassium  hydroxide. 

Put  6.8  grams  of  anthranilic  acid,  5.7  grams  of  chloracetic 
acid,  8.5  grams  of  dry  sodium  carbonate  and  50  cc.  of  water  in 
a  200  cc.  flask,  connect  with  an  upright  condenser  and  boil  for 
2  to  3  hours.  Cool,  add  hydrochloric  acid  in  slight  ex- 
cess, filter  off  the  precipitated  phenylglycine-0-carboxylic  acid, 

xNHCH2CO2H 
C6H/  ,  after  standing  for  some  hours  and  recrys- 

x:o2H 

tallize  it  from  water.  • 

Dissolve  4  grams  of  the  phenylglycine-o-carboxylic  acid  in 
17  cc.  of  sodium  hydroxide  (10  per  cent.),  evaporate  the  so- 
lution to  dryness  on  the  water-bath  and  dry  the  powdered  resi- 
due at  140°. 

In  a  not  too  small  nickel  crucible  melt  10  grams  of  sodium 
hydroxide  and  10  grams  of  potassium  hydroxide  and  heat  till 
the  water  is  expelled  and  the  hydroxides  are  in  a  state  of  quiet 
fusion.  Cool  to  270°,  measuring  the  temperature  with  a  ther- 
mometer enclosed  in  a  copper  or  iron  tube,  closed  below.  Add 
the  sodium  salt  previously  prepared,  stir  and  keep  the  mixture 
at  26o°-2jo°  for  ten  or  fifteen  minutes.  This  treatment 


AMINES  237 

causes    the    condensation     of     the     acid     to     indoxylic    acid, 
NH 


C(OH) 

When  the  mass  is  cold,  dissolve  it  in  50  cc.  of  water  and  boil 
gently  for  half  an  hour.  This  causes  the  loss  of  carbon 
dioxide  and  conversion  of  the  indoxylic  acid  to  indoxyl, 

NH 
C.HA  >^CH.     Add  100  cc.  of  water  and  draw  or  blow  a 


C(OH) 

rapid  current  of  air  through  the  solution  for  several  hours.  This 
will  cause  the  oxidation  and  condensation  of  two  molecules  of 
indoxyl  to  one  of  indigo.  Yield  about  i  gram. 

115.  Preparation  of  a  Complex  Secondary  Amine  from  a 
Primary  Amine  and  a  Bromine  Derivative  of  an  Ester.  —  Ani- 

/C02C2H5 
inomalonic  ester,    C6H.NHCH< 

XCOaC2H5 
Literature  —  Curtiss  :  Am.  Chem.  J.,  ig»  691. 

11.95  grams  ethyl  ester  of  bromomalonic  acid. 
9.3  grams  aniline. 

Put  in  a  small  flask  11.95  grams  (0.05  mol.)  of  the  ethyl 
ester  of  bromomalonic  acid  and  9.3  grams  (o.i  mol.)  of  aniline. 
Allow  the  mixture  to  stand  over  night  and  then  complete  the 
reaction  by  warming  for  half  an  hour  on  the  water-bath.  Cool, 
add  ether  gradually  to  precipitate  the  aniline  hydrobromide  and 
dissolve  the  ester.  Filter  from  the  hydrobromide,  wash  the 
ethereal  solution  in  a  separatory  funnel  two  or  three  times  with 
5  per  cent,  sulphuric  acid  to  remove  aniline  and  once  or  twice 
with  water.  Dry  the  solution  with  fused  potassium  carbonate, 
and  evaporate  the  ether  to  crystallization.  The  ester  may  be 
purified  by  recrystallization  from  alcohol.  It  crystallizes  in 
needles  which  melt  at  44°  -45°.  Yield  almost  quantitative. 


238  ORGANIC   CHEMISTRY 

CH      N 


CH       C       CH 
116.  Skraup's  Synthesis  of  Quinoline.  —  |  II       | 

CH      C      CH 


CH  CH 

Literature  —  Gerhardt:  Ann.,  42,  310;  44,  279;  Baeyer:  Ber.,  12,  460, 
1320;  Konigs:  Ibid,  12,,453;  13,  911;  Wyschnegradsky  :  Ibid,  12,  1480; 
Skraup,  Monatshefte,  i,  317;  2,  141;  J.  Walter:  J.  prakt.  Chem.,  49» 
549  ;  Knueppel  :  Ber.,  2Q»  703  ;  Marckwald  :  Ann.,  279,  3. 

24  grams  nitrobenzene. 

38  grams  aniline. 

100  grams  concentrated  sulphuric  acid. 

120  grams  glycerol. 

Put  in  a  liter  flask  the  mixture  given  above,  connect  with  a 
wide  upright  condenser,  warm  slowly  till  the  reaction  just  begins,1 
remove  the  flame  quickly  till  it  moderates,  and  then  boil  for  two 
hours.  Cool  somewhat,  add  100  cc.  of  water,  and  distil  in  a 
current  of  steam  (see  22,  p.  71)  as  long  as  the  distillate  smells 
of  nitrobenzene.  Cool,  add  300  cc.  of  caustic  soda  (3  cc.  = 
i  gram),  and  distil  over  the  quinoline  with  a  current  of  steam. 
To  destroy  the  aniline  which  is  present,  add  to  the  distillate 
50  cc.  of  concentrated  hydrochloric  acid,  and  then  a  strong  solu- 
tion of  sodium  nitrite,  till  the  solution  smells  of  nitrous  acid. 
Heat  to  boiling  till  the  diazonium  compound  is  decomposed  ; 
add  100  cc.  of  caustic  soda,  and  distil  the  quinoline  again  with 
water  vapor.  Collect  the  quinoline  with  a  little  ether,  distil  off 
the  ether,  dry  the  residue  with  solid  caustic  potash,  pour  off,  and 
distil.  Yield  about  40  grams. 

Quinoline  boils  at  237°.  It  gives  an  orange-yellow,  difficultly 
soluble  precipitate  with  chloroplatinic  acid,  (C9H7N)2H2PtCl6. 

The  nitrobenzene  used  in  the  synthesis  acts  as  an  oxidizing 
agent,  and  Knueppel  has  shown  that  it  may  be  replaced  with 
advantage  by  arsenic  acid.  The  reaction  is  , 

C6H5NH2  +  C3H803  +  O  =  C9H7N  +  4H2O. 

1  If  this  operation  is  conducted  carelessly  the  reaction  may  become  explosively  vio 
lent. 


AMINES  239 

The  same  reaction  may  be  applied  to  a  great  many  derivatives 
of  benzene,  naphthalene  and  anthracene. 

117.  Preparation  of  a  Quinazoline  from  an  Acyl  Anthranilic 
Nitrile.  —  2.7-Dimethyl-4-ketodihydroquinazoline  or  2.7-Dimethyl- 
4-hydroxyquinazoline. 

/N  --=  C.CH,  /N  -  C.CHS 

CH3C6H3/  n   CH3C6H/  | 

\CO  —  NH  \COH-  N 


Literature  —  General  discussion  of  quinazolines,  Bogert:  J.  Am.  Chem. 
Soc.,  32»  784;  Preparation  of  Dimethyl-ketodihydroquinazoline,  Bogert 
and  Hoffman:  J.  Am.  Chem.  Soc.,  27,  1296,  1299. 

4  grams  homoanthranilic  nitrile. 

5  cc.  acetic  anhydride. 

1.5  grams  acetyl  homoanthranilic  nitrile. 
50  cc.  potassium  hydroxide  (10  per  cent.). 
50  cc.  hydrogen  peroxide  (3  per  cent). 

/CH,       i. 
Put  4  grams  of  homoanthranilic  nitrile,1  C6H3  —  NH2      3.       , 

\CN       4. 

and  5  cc.  of  acetic  anhydride  in  a  long  test-tube  and  boil  gently 
with  a  micro  burner  for  two  hours,  covering  the  mouth  of  the 
tube  with  a  small  watch-glass  and  taking  care  not  to  boil  so  vig- 
orously that  the  anhydride  escapes.  Pour  the  solution  into  water 
and  crystallize  the  acetyl  homoanthranilic  nitrile  from  dilute 
acetic  acid  and  from  alcohol.  It  crystallizes  in  colorless  needles, 
which  melt  at  136°. 

Put  1.5  grams  of  acetyl  homoanthranilic  nitrile  in  a  150  cc. 
flask,  add  50  cc.  of  a  10  per  cent,  solution  of  potassium  hydroxide 
and  50  cc.  of  a  3  per  cent.  ("10  volume")  solution  of  hydrogen 
peroxide  and  warm  at  4O°-5o°  for  two  hours.  The  alkaline 

XCH3     I. 
1  The  nitro  nitrile,  CeH3  —  NOo    3.  ,  may  be  prepared  by  Sandmeyer's  reaction  (p.  131) 

^CN      4. 

from  wx-nitro-^-toluidine  (p.  213)  (see  Bogert  and  Hoffman,  J.  Am.  Chem.  Soc.,  27,  1294 
Bogert  and  Hand,  Ibid,  (24,  1035)  Noyes,  Am.  Chem.  J.,  10,  477).  The  nitro-nitrile  is  re- 
duced to  tht  amino-nitrile  by  stannous  chloride  and  hydrochloric  acid  (Bogert  and  Hoff- 
man, J.  Am.  Chem.  Soc.,  27,  1295). 


240  ORGANIC   CHICMISTKV 

hydrogen  peroxide  solution  saponifies  the  nitrile  to  the  amide 
and  the  latter  condenses  to  form  the  quinazoline.  The  latter  dis- 
solves either  in  strong  acids  or  in  strong  bases  (why)  ?  Add 
10  cc.  of  concentrated  hydrochloric  acid  (1.19)  and  then  a 
slight  excess  of  ammonia.  Crystallize  the  precipitated  quinazo- 
line from  alcohol. 

2.7-Dimethyl-4-ketodihydroquinazoline  crystallizes  in  needles 
which  melt  at  255°. 

118.  Preparation  of  a  Derivative  of  Pyridine  by  Condensation. 

CH3 

C 

/% 

-  Collidinedicarboxyllic  ester,    C0H5CO,  —  C         C  —  CO2C2H6. 

II 

C         C 

/  v  \ 

CH3          N         CH3 

Literature — Hantsch :  Ann.,  215,  8;  Michael:  Ibid,  225,  123;  Bamberger : 
Ber.,  24,  1763. 

20  grams  acetoacetic  ester. 

5  grams  aldehyde  ammonia. 

10  grams  dihydrocollidinedicarboxyllic  ester. 

Arsenious  anhydride. 

Nitric  acid    (sp.  gr.   1.30-1.33). 

Put  in  a  small  beaker  20  grams  of  acetoacetic  ester,  and  add 
five  grams  of  aldehyde  ammonia.  Warm  gently  till  the  reac- 
tion begins,  remove  the  flame  for  a  short  time,  and  then  boil,  with 
stirring,  for  four  or  five  minutes  in  all.  Add  a  little  alcohol, 
and  allow  to  cool  till  the  dihydrocollidinedicarboxyllic  ester  crys- 
tallizes; filter,  wash  once  with  dilute  alcohol,  and  then  with 
water.  A  small  amount  of  less  pure  ester  may  be  obtained  by 
diluting  the  filtrate. 

The  reaction  takes  place  in  some  such  manner  as  the  follow- 
ing: 


AMINES  241 

CH3 
C2H5  —  CO,  —  C  ;OH  H;  C^OH  HiCH  —  CO2C,H5  = 

ir       :\:i:i::/ 

CH  N;H2  0;C 

CH3  CH3 

CH3 

C.,H5CO,  —  C  ==  C  —  CH  —  C02C.,HS 

4-  3H,0. 
CH3  —  CH  —  N  =  C  —  CH:i 

Put  10  grams  of  the  crude  ester  in  a  small  flask,  add  20  cc.  of 
alcohol,  and  pass  in  a  rapid  stream  of  the  oxides  of  nitrogen, 
generated  by  warming  arsenious  oxide  with  nitric  acid  of  sp. 
gr.  1.301.33,  passing  the  gases  through  an  empty  Drechsel 
wash-bottle  to  condense  water.  Rubber  connections  must  be 
avoided  as  far  as  possible,  because  the  gas  attacks  them.  Con- 
tinue the  passage  of  the  gas  till  a  drop  of  the  solution  dissolves 
clear  in  dilute  hydrochloric  acid.  Evaporate  the  alcohol  on  the 
water-bath,  add  ?.  strong  solution  of  sodium  carbonate,  and  take 
up  the  collidinedicarboxyllic  ester  with  ether.  Dry  the  ethereal 
solution  with  ignited  potassium  carbonate,  and  distil  from  a  small 
distilling  bulb.  Yield  7  to  8  grams. 

The  dihydro  ester  crystallizes  in  colorless  plates,  which  melt 
at  131°.  Its  solutions  show  a  beautiful  blue  fluorescence.  It  is 
almost  insoluble  in  water,  and  in  dilute  acids,  difficultly  soluble 
in  cold  alcohol,  easily  soluble  in  hot  alcohol,  and  in  chloroform. 
It  dissolves  in  concentrated  hydrochloric  or  sulphuric  acid. 

Collidinedicarboxyllic  diethyl  ester  boils  at  308° -310°.  It  is 
easily  saponified  by  alcoholic  potash,  giving  a  potassium  salt 
difficultly  soluble  in  alcohol.  Collidine  may  be  obtained  from  this 
potassium  salt  by  mixing  it  with  calcium  hydroxide  and  distil- 
ling. 

119.  Preparation  of  a  Leuco  Base  and  Dye  by  Condensation  of 
an  Aldehyde  with  an  Aromatic  Amine. — Malachite  Green. 

(  /,C6H4  ~=  N(CH8),Cn 

3  I  C  H.  --  C<  |  .     2ZnCl,.2H,O. 

\C.H4    -N(CHJ,      ! 


242  ORGANIC   CHEMISTRY 

Literature.  —  Condensation  of  aromatic  hydrocarbons  with  aldehydes, 
Baeyer:  Ber.,  6,  963;  Preparation  of  Leucomalachite  green,  O.  Fischer: 
Ann.,  206,  83,  122,  129;  Dobner:  Ann.,  217,  250-253;  E.  Fischer:  Anleiting 
z.  Darst,  org.  Praparte,  p.  71  ;  Henle  :  Anleitung  zur  anorg.  prap.  prakti- 
cum  p.  153;  Preparation  and  constitution  of  rosaniline  and  pararosaniline, 
O.  and  E.  Fischer:  Ann.,  194,  242,  285;  Ber.,  n,  1079;  13,  2204;  Crystal- 
violet,  Hofmann  :  Ber.,  18,  767;  Carbinol  and  quinoid  formulae,  Friedlander: 
Ber.,  26,  173;  Nomenclature  and  classification  of  triphenylmethane  dyesr 
Baeyer  and  Villiger  :  Ber.,  37,  597,  2848;  Theory  of  colored  and  colorless 
compounds,  Hantsch  :  Ber.,  33,  278,  752  ;  38,  2143  ;  Gomberg  :  Ber.,  40,  1868, 
1875;  Baeyer  and  Villiger:  Ber.,  37,  597,  2848;  38,  569;  Ann.,  354>  152; 
Wilstatter  :  Ber.,  41,  1458  ;  Curtiss  :  J.  Am.  Chem.  Soc.,  32»  795  ;  Isorrepsis, 
Baly  and  Stewart:  J.  Chem.  Soc.,  89,  498,  513;  Development  of  the  coal 
tar  dyes,  Caro  :  Ber.,  25,  R.  955. 

12  grams   dimethyl   aniline. 

5   grams   benzaldehyde. 

10  grams   fused  zinc  chloride. 

3.3  grams   leuco  base. 

40  cc.  normal  hydrochloric  acid. 

2.4  grams  lead  peroxide. 

3.5  grams  zinc  chloride. 
Saturated  solution   of   salt. 

Put  12  grams  of  dimethylaniline,  5  grams  of  benzaldehyde  and 
10  grams  of  fused  zinc  chloride  in  a  porcelain  dish  and  warm 
on  a  water-bath  for  some  hours,  stirring  occasionally  and  add- 
ing a  few  drops  of  water  if  the  mixture  becomes  too  vis- 
cous. Transfer  the  mixture  to  a  flask  or  distilling  bulb  and 
drive  out  the  excess  of  dimethyl  aniline  with  a  current  of 
steam.  Cool,  pour  off  the  aqueous  solution  of  zinc  chloride, 
dissolve  the  leuco  base,  tetramethyldiaminotriphenylmethane, 

4  -  N(CH8), 

,    in  a  considerable  amount   of  hot 

C6H4N(CH3)2 

alcohol,  filter,  if  the  solution  is  not  clear,  and  allow  to  crystal- 
lize. If  the  base  separates  as  an  oil  at  first,  dissolve  again  in 
more  alcohol.  After  the  crystals  have  been  separated  an  ad- 
ditional crop  may  be  obtained  by  evaporating  the  mother-liquors. 
The  base  melts  at  102°. 


, 
CH^ 

\ 


AMINES  243 

Dissolve  3.3  grams  of  the  leuco  compound  in  40  cc.  of  hot, 
normal  hydrochloric  acid,  dilute  with  300  cc.  of  water  and  add 
gradually,  with  vigorous  shaking,  2.4  grams  of  lead  peroxide 
mixed  with  about  20  cc.  of  water1.  Shake  vigorously  for  about 
10  minutes  in  all.  Add  an  aqueous  solution  of  3.5  grams  of  zinc 
chloride  and  then,  gradually,  a  saturated  solution  of  salt  until  a 
portion  of  the  mixture  gives  a  colorless  nitrate.  Filter  and  wash 
once  with  a  salt  solution.  Dissolve  the  compound  in  hot  water 
and  reprecipitate  again  with  a  saturated  salt  solution. 

Dissolve  a  little  of  the  malachite  green  in  strong  hydrochloric 
acid  and  note  the  effect  of  dilution  with  water.  Dissolve  some 
of  the  dye  in  water  and  add  ammonia,  then  dilute  hydrochloric 
acid.  Reduce  some  of  the  substance  to  the  leuco  base  by  means 
of  zinc  and  dilute  hydrochloric  acid.  See  Dobner:  Ann.,  217, 
251  and  252. 

1  The  per  cent,  of  pure  lead  peroxide  in  the  reagent  must  be  known  and  enough 
taken  to  give  2.4  grams  of  the  pure  compound. 


Chapter    XIV 


DIAZO,  HYDRAZO,  NITROSO  AND  OTHER 
NITROGEN  COMPOUNDS 

A  considerable  number  of  other  nitrogen  compounds  beside 
amines  and  nitro  derivatives  are  known.  Most  of  these  are  ob- 
tained by  reduction  of  nitro  compounds,  by  oxidation  of  amines, 
or  by  condensations  with  the  use  of  the  compounds  resulting 
from  such  reduction  or  oxidation.  Unless  otherwise  stated,  the 
following  methods  apply  to  the  aromatic  series  only.  In  some 
cases  similar  derivatives  of  the  marsh  gas  series  are  known,  but 
usually  they  require  different  methods  of  preparation. 

Azoxy  compounds  are  formed  by  boiling  nitro  compounds  with 
a  solution  of  caustic  potash  in  methyl  or  ethyl  alcohol,  or  with 
a  solution  of  sodium  ethylate,  or  methylate,  the  alcohol  acting  as 
the  reducing  agent. 

2R-NO2  30  R— N— N— R. 

v 

O 

The  method  cannot  be  applied  to  compounds  having  a  methyl 
group  para  to  the  nitro  group,  because  condensation  to  deriva- 
tives  of  dibenzyl,   C6H5CH2CH2C6H,,   or   stilbene,   C6H5CH   : 
CHC6H5,  takes  place. 

Azo  compounds  are  prepared  by  the  reduction  of  azoxy  com- 
pounds by  distillation  with  iron  filings,  by  the  direct  reduction 
of  nitro  compounds  with  zinc  dust  and  alcoholic  potash,  or  by 
the  oxidation  of  hydrazo  compounds  by  means  of  the  oxygen  of 
the  air  acting  on  a  solution  in  alcohol  containing  a  little  alkali. 
R-N— N-R  —  O  R— N^N— R. 


O 

2R_NO2  40     =     R— N=N— R. 

R_NH— NH— R   -f   O     =     R— N=N— R  +   H26. 
Aminoazo,    R — N=N — R. — NH2,     and    hydroxyazo     (usually 


DIAZO,    HYDRAZO,    NITROSO,    ETC.  245 

called  in  German  text-books  "oxyazo"),  R — N=N — R — OH, 
compounds  are  formed  by  the  condensation  of  diazonium 
compounds,  with  amines  or  phenols.  As  the  condensation 
takes  place  usually  in  neutral,  or  slightly  acid  solutions,  but 
does,  not.  as  a  rule,  occur  in  either  strongly  alkaline  or  strong- 
ly acid  solutions,  Bamberger  supposes  the  reaction  to  take 
place  between  the  diazonium  hydroxide  and  the  other  compound. 
/Ber.,  28,  444.) 

R— N  =  X— OH    +    H— R— NH2     == 
R_N=N— R— NH2  +  H2O. 

This  kind  of  condensation  takes  place  most  readily  with  ter- 
tiary   amines,    and    with    primary    metadiamines.     Primary    and 
secondary   amines,   on  the  other  hand,   condense  in  acetic   acid 
solutions,  with  the  formation  of  diazoamino  compounds. 
R_N=N— OH   +   R— NH2     =     R— N=N— NHR   +   H2O. 

These  diazoamino  compounds,  when  allowed  to  stand  with 
cold  dilute  hydrochloric  acid,  or  when  warmed  with  the  hydro- 
chloride  of  the  amine,  dissolved  in  the  free  amine,  usually  pass 
over  into  the  corresponding  aminoazo  compound ;  e.g. : 

C6H5— N=N— NHC6H5  — >  C6H5— N= N-C6H4NH2. 

Diazoamino  benzene  Aminoazobenzene 

This  combination  ("Kuppelung")  of  diazonium  compounds 
with  amines  and  phenols,  and  the  transformation  of  diazoamino 
into  aminoazo  compounds,  are  of  great  technical  importance.  O. 
N.  Witt  has  pointed  out  that  dye-stuffs  must  have  two  character- 
istics; they  must  have  a  color  group  ("chromophore"),  e.g.,  the 
azo,  or  nitio  group,  and  they  must  also  have  a  salt- forming 
group,  ("auxochrome"),  e.g.,  hydroxyl,  or  the  amino  group, 
which  will  enable  the  substance  to  combine  with  the  fibei 
in  dyeing.  The  azo  compounds  are  all  of  them  colored,  but  only 
those  of  them  which  contain  some  "auxochrome"  group  as  well 
can  be  used  in  dyeing. 

All  organic  coloring  matters  are  changed  to  colorless  com- 
pounds by  reduction.  These  colorless  compounds  have  received 
the  general  name  of  "leuco"  compounds  (see  p.  241  also) 
("Leukoverbindungen,"  from  Greek  Aev*os.  white).  The  leuco 


246  ORGANIC    CHEMISTRY 

compounds  corresponding  to  the  azo  compounds  are  the  hydrazo 
compounds.  These  may  be  prepared  from  the  azo  compounds 
by  reduction  with  alcoholic  ammonium  sulphide,  or  with  zinc 
dust  and  alcoholic  potash  or  soda.  They  may  also  be  prepared 
by  direct  reduction  of  nitro  compounds  with  zinc  dust  and  al- 
coholic potash. 

R_N=N— R  +  2H     =     R_NH— NH— R. 
2R— NOa  +  loH  R_NH— NH— R  +  4H2O. 

Diazonium  compounds  are  formed  by  the  action  of  nitrous 
acid  on  amines  in  acid  solutions. 

RNHSHC1  +  HNO,  ==   R  —  N  =  N  +-  2H2O. 

I 
Cl 

On  account  of  their  instability,  diazonium  compounds  are  not 
usually  separated,  but  are  used  for  synthetical  purposes  im- 
mediately after  preparation.  Several  illustrations  of  such  use 
have  already  been  given.  (See  pp.  702,  131,  201.) 

Hydrazines  are  prepared  by  the  reduction  of  diazonium  com- 
pounds with  stannous  chloride,  with  acid  sodium  sulphite,  or  with 
acid  sodium  sulphite,  zinc  dust  and  acetic  acid,  followed  by  the 
decomposition  of  the  resulting  sulphonic  acid  with  hydrochloric 
acid. 

R  -  N  =  N  -f  2SnCl2  +  4HC1  R— NH— NH.>HCl-h2SnCl4. 

I 
Cl 

R  —  N  =  N  +  HNaSO,  R— N— N— SOsNa  +  HC1. 

I 
Cl 

R_N=N— SO3Na  +  2H     =     R— NH— NH— SO3Na. 
R_NH— NH— SO3Na  +   HC1   +   H0O     = 

R— NH— NH2HC1  +  NaHSO4. 

Hydrazones  are  formed  by  the  condensation  of  hydrazines 
with  aldehydes  or  ketones,  usually  in  neutral  or  acetic  acid  so- 
lution. 

R\  /R 

R_NH— NH.+       >CO    =    R-NH— N— C<       +  H,O. 

R/  \R 


DIAZO,    HYDRA2O,    NITROSO,    ETC.  247 

Hydrazones  are  also  formed  by  the  condensation  of  diazo- 
nium  compounds  with  substances  containing  a  methylene  group 
between  two  carboxyl  groups.  Owing  to  a  different  view  of  the 
structure  of  these  compounds,  which  prevailed  before  they  had 
been  fully  studied,  they  are  frequently  called  azo  compounds. 

C6H5  — N  =  NOH  +  CH./ 

\COAH, 

OH  H 

C,H5  —  NH        N  —  C  —  CO2C2H5  = 

COAH, 


/C02C2H5 
H   —  NH  —  N  ==  C< 

\COH 


C6H5  —  NH  —  N  ==  C<  HfO. 


i^i**i 

Hydrazone  of  mesoxalic  acid 

On  the  supposition  that  the  structure  was  represented  by  the 

/CO.C.H, 

formula  C6HS—N=N—CH<  ,    this    was    called    ben- 

NCO,C,H, 

zenazomalonic  ester,  a  name  still  used. 

Hydrazides  are  formed  by  the  condensation  of  hydrazines, 
with  compounds  containing  hydroxyl,  the  condensation  taking 
place  readily  only  when  the  hydroxyl  is  more  or  less  acid  in  its 
properties. 

R— NH— NHX 

R—NH  -NH2  +  RCOOH  >C  =  O  +  H2O. 

R/ 

The  name  is  given  from  the  analogy  with  amides. 

Osazones  are  formed  by  the  action  of  an  excess  of  phenyl  hy- 

j 

'    CHOH 

drazine  on  substances  containing  the  group   \  .     A  part  of 

CO 
I 

the  phenyl  hydrazine  combines  at  once  to  form  a  hydrazone,  a 
second  part  oxidizes  the  alcoholic  group  to  a  ketonic  or  aide- 


248  ORGANIC    CHEMISTRY 

hyde  group,   and  the  latter  reacts  with  more  of  the  hydrazine. 

I 

C  =  N  —  NHC6H5 
giving  finally  the  group,     |  .       The    osazones 

C  =  N  —  NHC6H, 

I 
have  been   of   especial  importance  in  the  study  of   sugars. 

120.  Preparation  of  a  Hydrazo  Compound. — Hydrazobenzene, 
C6H5— NH— NH— C6H5. 

Literature — Hofmann :  Jahresb.,  1863,  424;  Alexejew:  Ztschr.  Chem., 
1867,  33 ;  1868,  497 ;  E.  Erdmann :  Ztschr.  angew.  Chem.,  1893,  163. 

30  grams  nitrobenzene. 

200  cc.   alcohol. 

40  cc.  sodium  hydroxide    (3  cc.   -  -    i   gram). 

45  grams  zinc  dust. 

Put  in  a  500  cc.  flask  200  cc.  of  alcohol,  30  grams  of  nitro- 
benzene, and  40  cc.  of  a  solution  of  caustic  soda  (3  cc  =  i 
gram).  Heat  on  a  water-bath  to  about  75°,  putting  in  the 
mouth  of  the  flask  a  cork  hearing  a  tube  to  act  as  an  air  con- 
denser. Add  a  small  amount  of  zinc  dust,  shake  and  add  more, 
in  small  portions,  till  the  reaction  begins.  If  the  action  becomes 
violent,  check  it  by  dipping  the  flask  in  cold  water.  Continue 
the  warming  and  addition  of  zinc  dust  till  the  solution  becomes 
nearly  colorless.  Filter  hot  on  a  plate,  cool  quickly,  filter  off 
the  hydrazobenzene  as  rapidly  as  possible,  wash  with  a  little 
alcohol,  transfer  it  to  a  flask  and  add  at  once  some  alcohol  con- 
taining a  little  ammonium  sulphide  to  prevent  oxidation.  Boil 
the  residue  of  zinc  dust  with  the  mother-liquors,  filter  and 
separate  the  hydrazobenzene  as  before,  and  repeat  a  third  time. 
Then  recrystallize  the  whole  from  hot  alcohol  containing  am- 
monium sulphide,,  working  as  rapidly  as  possible,  to  prevent  oxi- 
dation, and  finally  dry  the  product  in  a  vacuum  desiccator,  over 
sulphuric  acid.  In  recrystallizing,  water  may  be  added  to  the 
hot,  filtered  alcoholic  solution  till  it  begins  to  be  turbid,  to  cause 
the  more  complete  separation  of  the  hydrazobenzene,  and  the 
product  may  be  washed  with  dilute,  instead  of  pure  alcohol.  It 
may  also  be  crystallized  from  ligrom.  Yield  19  to  20  grams. 


DIAZO,    HYDRAZO,    NITROSO,    ETC.  249 

Hydrazobenzene  crystallizes  in  colorless  leaflets,  which  melt  at 
131°.  It  is  easily  soluble  ;n  alcohol  and  ether,  almost  insoluble 
in  water.  It  is  very  easily  converted  into  azobenzene,  even  by 
the  oxygen  of  the  air.  By  warming  with  hydrochloric  acid,  it  is 
converted  into  benzidine,  NH2 — C6H4 — C6H4 — NH2.  It  is  de- 
composed by  heat  into  azobenzene  and  aniline. 

121.  Preparation  of  an  Azo  Compound. — Azobenzene, 

C6H5— N=N— C6H5. 

Literature — Mitscherlich :  Ann.,  12,  3ii;-Zinin:  J.  prakt.  Chem.,  36, 
93,  (1845)  ;  Claus:  Ber.,  8,  37;  Griess :  Ibid,  9,  132;  Frankland  and  Louis: 
J.  Chem.  Soc.,  37,  560,  (1880);  Spiegel:  Ber.,  18,  1481  ;  Mills:  J.  Chem. 
Soc.,  65,  51,  (1894}:  Steromeric  forms,  Gortner  and  Gortner :  J.  Am. 
Chem.  Soc.,  32,  1294. 

10  grams  hydrazobenzene. 
170  cc.  alcohol. 

1  cc.  sodium  hydroxide  (3  cc.  =  i  gram). 

Put  in  a  300  cc.  flask  10  grams  of  hydrazobenzene,  170  cc.  of 
alcohol,  and  i  cc.  of  a  solution  of  caustic  soda.  Close  the  flask 
with  a  stopper  bearing  an  upright  condenser,  and  a  glass  tube 
leading  nearly  to  the  bottom  of  the  flask.  Heat  on  a  water-bath 
and  draw  or  force  through  the  solution  a  slow  current  of  air 
for  three  to  four  hours.  Filter,  if  necessary,  distil  off  most  of 
the  alcohol  and  allow  the  azo-benzene  to  crystallize  after  adding 
a  little  water.  Yield  7  to  8  grams. 

Azobenzene  crystallizes  in  red  plates,  which  melt  at  68°.  It 
boils  without  decomposition  at  295°.  It  is  soluble  in  12  parts  of 
alcohol  at  16°. 

122.  Preparation  of  a  Diazonium  Compound. — Benzene  diazo- 

nium  chloride,  C6H5  —  N  =  N. 

Cl 

Literature.— Griess :  Ann.,  113,  201;  "7,  i;  "i,  257;  i37»  39;  Ber., 
24,  R.,  1007;  V  .Meyer  and  Ambiihl :  Ibid,  8,  1073;  Knoevenagel:  Ibid,  *3, 
2994;  Hausser  and  Miiller :  Bull.  soc.  chim.  [3],  9,  353,  (1893). 

2  grams  aniline  hydrochloridei 
8  cc.  alcohol. 

2  cc.   (1.8  grams)  amyl  nitrite,  or 
1.3  cc.    (1.23  grams)   ethyl  nitrite. 


250  ORGANIC   CHEMISTRY 

Dissolve  2  grams  of  aniline  hydrochloride  in  8  cc.  of  abso- 
lute alcohol  in  a  test-tube.  Cool  with  ice-water,  add  a  drop  of 
concentrated  hydrochloric  acid,  and  then  very  slowly,  with  cool- 
and  and  stirring,  2  cc.  of  amyl  nitrite,  or  1.3  cc.  of  ethyl  nitrite.1 
Allow  to  stand  in  ice-water  for  a  short  time,  and  then  filter  off 
the  benzene  diazonium  chloride  and  wash  it  with  a  very  little 
alcohol,  containing  a  1'ttle  hydrochloric  acid,  and  with  ether. 

Separate  into  several  portions  and  dry  on  filter-paper,  in  the 
air.  On  account  of  the  explosive  character,  the  portions  dried 
should  not  exceed  0.1-0.2  gram  each. 

Small  portions  may  be  warmed  with  water,  alcohol,  or  con- 
centrated hydrochloric  acid,  to  illustrate  the  decompositions  of 
the  substance,  but  for  most  purposes  of  synthesis,  the  free  di- 
azonium compounds,  or  salts,  are  not  prepared.  See  pp.  70, 
131,  201. 

123.  Preparation  of  an  Amino-azo  Compound  through  the  Di- 
azoamino  Compound.  — />-Aminoazobenzene, 

/N-N-C.H,  (i) 
C6H/ 

XNH2  (4) 

Literature — Griess :  Ann.,  121,  258;  Staedel  and  Bauer:  Ber.,  19,  1952; 
Niementowski    and    Roszkowski :    Z.    physik.    Chem.,    22,    145. 

50  cc.  aniline. 

60  cc.  concentrated  hydrochloric  acid. 

13  grams  aniline  hydrochloride. 

200  cc.  water. 

3.5  grams  sodium  nitrite. 

17.5  cc.  water. 

10  grams  crystallized  sodium  acetate. 

5   grams  diazoaminobenzene. 

15  grams  aniline. 

3  grams  aniline  hydrochloride. 

i  Ethyl  nitrite  may  be  prepared  a*  follows:  Prepare  a  solution  of  10  grams  of  sodium 
nitrite  in  50  cc.  of  water  and  5  cc.  of  alcohol,  and  a  second  solution  of  5  cc.  of  concentrated 
sulphuric  acid,  50  cc.  of  water  and  5  cc.  of  alcnhol.  Cool  each  to  o°,  and  add  the  acid  solu- 
tion to  the  nitrite  solution,  with  a  pipette,  which  is  inserted  beneath  the  surface  of  the 
liquid,  cooline  thoroughly.  After  a  few  minutes,  separate  the  ethyl  nitrite,  which  rises 
to  the  top  of  the  liquid,  using  a  cold  separatory  funnel.  Keep  the  nitrite  in  a  tube,  sur- 
rounded with  ice.  It  boils  at  17°.  If  larger  quantities  of  the  nitrite  are  desired,  the  solu- 
tions may  be  prepared  in  the  proportions  given,  and  the  nitrite  solution  put  in  a  flask  or 
distilling  bulb,  connected  with  a  condenser,  fed  with  ice-water.  The  solutions  should  be 
at  2o0-2.s°.  On  running  the  acid  solution  in  slowlv,  the  ethyl  nitrite  will  distil  over,  and 
may  be  collected  in  a  receiver,  surrounded  with  ice.  (Wallach  and  Otto:  Ann.,  053,  251.) 


DIAZO,    HYDRAZO,    NITROSO,    ETC.  251 

Prepare  some  aniline  hydrochloride  by  dissolving  50  cc.  of 
aniline  in  6  cc.  of  concentrated  hydrochloric  acid,  cooling  thor- 
oughly, filtering  with  a  plate  on  a  hardened  filter,  and  drying  on 
the  water-bath. 

Dissolve  13  grams  of  the  aniline  chloride  in  200  cc.  of  water, 
bring  the  temperature  to  25°,  and  add,  with  stirring,  3.5  grams 
of  sodium  nitrite,  dissolved  in  17.5  cc.  of  water.  Keep  the  tem- 
perature at  27°-3O°  by  cooling,  if  necessary.  Add,  at  once,  a 
previously  prepared  solution  of  10  grams  of  crystallized  sodium 
acetate,  stir  thoroughly  and  allow  the  whole  to  stand  for  15 
minutes.  Filter  off  the  diazoaminobenzene,  wash  and  dry  in 
vacuo  over  sulphuric  acid.  The  yield  is  9  to  10  grams.  To 
obtain  a  pure,  light  yellow  product  it  is  best  to  dissolve  immed- 
iately, without  drying,  in  ligroin,  on  the  steam-bath,  pour  off 
from  the  water  and  cool  the  ligroin  solution  till  crystallization  is 
complete. 

Dissolve  5  grams  of  the  dry  diazoaminobenzene  in  15  cc.  of 
aniline,  in  a  small  flask,  add  3  grams  of  dry,  powdered  aniline 
hydrochloride,  warm  in  a  water-bath  at  40°,  for  an  hour,  and  al- 
low the  mass  to  stand  for  a  day,  or  until  the  solution  no  longer 
evolves  nitrogen  when  a  small  portion  is  warmed  with  alcohol 
and  hydrochloric  acid.  Add  40  cc.  of  hydrochloric  acid  (sp.  gr. 
i.io),  cool,  filter,  and  wash  with  dilute  hydrochloric  acid.  Dis- 
solve the  hydrochloride  of  the  aminoazobenzene  in  about  500  cc. 
of  hot  water,  adding  enough  hydrochloric  acid  to  prevent  hy- 
drolysis but  not  more.  Filter,  if  necessary,  and  add  20  to  25  cc. 
of  concentrated  hydrochloric  acid.  On  cooling,  the  hydrochlo- 
ride will  separate  almost  completely  in  crystalline  form.  Filter, 
wash  with  dilute  acid,  and  dry. 

If  the  free  aminoazobenzene  is  desired,  it  can  be  obtained  by 
warming  the  chloride  with  twice  its  weight  of  alcohol,  and  adding 
concentrated  ammonia  till  it  dissolves.  On  further  addition  of 
water,  the  base  separates  in  orange-yellow  leaflets,  which  may 
be  recrystallized  from  benzene.  Yield  of  the  chloride  about 
4^  grams. 

^-Aminoazobenzene  crystallizes  in  orange-yellow,  rhombic 
prisms,  which  melt  at  127°,  and  boil  without  decomposition  at 


252  ORGANIC    CHEMISTRY 

360°.  It  is  almost  insoluble  in  water,  easily  soluble  in  alcohol 
and  ether.  It  is  reduced  by  tin  and  hydrochloric  acid  to  aniline 
and  paraphenylenediamine.  The  chloride  is  hydrolyzed  by  water 
It  is  known  as  aniline  yellow,  and  in  sb'ghtly  acid  solution  colors 
wool  and  silk  intensely  yellow. 

Diazoaminobenzene  melts  at  98°,  and  is  slightly  explosive. 

124.  Preparation  of  an  Azo  Compound  by  the  Combination 
of  a  Diazonium  Compound  with  an  Amine. — />-Sulphobenzene- 
azo-a-napthylamine, 

SOSH  NH, 


(4)-Sulphobenzene-azo~(4)-amino-(  i ) -'naphthalene. 
Literature — Griess  :  Ber.,  12,  427. 

5  grams  sulphanilic  acid. 

10  cc.  sodium  hydroxide  (10  per  cent.). 
200  cc.  water. 

10  cc.  hydrochloric  acid  (sp.  gr.  i.i). 

1.7  grams  sodium  nitrite. 
8.5  cc.  water. 

3.5  grams  a-naphthylamine. 

6  cc.  hydrochloric  acid   (sp.  gr.  i.i). 
200  cc.  water. 

Dissolve  5  grams  of  sulphanilic  acid  in  10  cc.  of  sodium  hy- 
droxide and  20  cc.  of  water,  by  warming  in  a  flask.  Cool,  di- 
lute to  about  200  cc.,  add  10  cc.  of  hydrochloric  acid  (i.i)  and 
then  1.7  grams  of  sodium  nitrite  dissolved  in  8.5  cc.  of  water. 
Dissolve  3.5  grams  of  a-naphthylamine  in  6  cc.  of  hydrochloric 
acid  and  200  cc.  of  hot  water.  Cool,  and  add  the  solution  of 
paradiazonium  benzene  sulphonic  acid.  Mix  thoroughly  by 


UIAZO,    HYDRAZO,    NITROSO,    ETC.  253 

pouring  from  one  beaker  to  another  and  back  several  times. 
Allow  to  stand  for  several  hours,  then  heat  on  the  water-bath,  or 
over  the  free  flame,  till  the  precipitate  becomes  crystalline,  and 
much  less  voluminous.  Filter  hot,  and  wash. 

a-Naphthylamine-azobenzene-/>-sulphonic  acid  crystallizes  in 
microscopic  needles  of  a  dark  violet  color.  It  is  almost  insolu- 
ble, even  in  boiling  water,  and  is  also  very  difficultly  soluble  in 
alcohol.  The  dilute  solutions  are  of  a  bright  red  or  pink  color, 
and,  since  the  compound  is  formed  quantitatively  when  nitrous 
acid  acts  on  an  excess  of  an  acid  solution  containing  sulphanilic 
acid  and  a-naphthylamine,  it  is  often  used  for  the  determination 
of  nitrites  in  potable  water. 

Since  the  substance  is  a  sulphonic  acid,  it  dissolves  to  clear 
orange-red  solutions  in  very  dilute  solutions  of  caustic  soda,  or 
ammonia,  but  the  addition  of  more  sodium  hydroxide  to  such 
solutions,  even  if  quite  dilute,  will  cause  the  precipitation  of  the 
red,  crystalline,  sodium  salt,  C16H12N3SO3Na. 

125.  Preparation  of  an  Azo  Compound  by  Coupling  a  Diazo- 
nium  Compound  with  an  Amine. — Helianthine   (Methyl  orange, 
Sodium  salt  of  4,4-Dimethylaminoazobenzene  sulphonic  acid). 
(CB3)2NC6H4— N=N— CaH4— SO3Na. 

Literature — Griess :  Ber.,  10,  258 ;  Theory  of  indicators,  Kremann :  Z. 
anorg.  Chem.,  33>  87 ;  Bredig :  Z.  anorg.  Chem.,  34»  -202 ;  Stieglitz :  J.  Am. 
Chem.  Soc.,  25,  1112:  Veley:  Z.  phys.  Ch.,  57»  148;  A.  A.  Noyes:  J.  Am. 
Chem.  Soc.,  32i  815;  Preparation  by  the  sulphonation  of  dimethylamino- 
azobenzene,  Nolting:  Ber.,  20,  2996. 

Solution  of  diazobenzene  sulphonic  acid. 

15  grams  ice. 

10  cc.  sodium  hydroxide   (10  per  cent.). 

3  grams  dimethyl  aniline. 

\y2   grams  glacial  acetic  acid. 

3  grams  sodium  hydroxide. 

15  cc.  water. 

Prepare  a  solution  of  ^-diazobenzene  sulphonic  acid  as  de- 
scribed in  the  preceding  preparation.  Add  15  grams  of  ice  and 
10  cc.  of  sodium  hydroxide,  (10  per  cent),  then,  at  once,  a  mix- 


254  ORGANIC   CHEMISTRY 

ture  of  3  grams  of  dimethyl  aniline  and  1^2  grams  of  glacial 
acetic  acid.  After  5-10  minutes  add  10  cc.  of  a  solution  of  so- 
dium hydroxide  (3  cc.  =  I  gram).  Filter  on  a  hardened  filter, 
suck  dry  and  recrystallize  the  sodium  salt  (methyl  orange) 
from  water. 

If  anthranilic  acid  is  used  instead  of  sulphanilic  acid  for  this 
preparation,  methyl  red,  (CH3)2N.C6H4— N=N— C6H4CO2H 
will  be  obtained.  It  is  a  valuable  indicator  for  weak  bases.  (Ber., 
40,  2698.) 

126.  Preparation  of  a  Hydrazine. — Phenyl  hydrazine, 
C6H6NHNH2. 

Literature — E.  Fischer:  Ann.,  190,  67;  Ber.,  17,  572;  V.  Meyer,  u. 
Lecco:  Ibid,  16,  2976;  Reychler:  Ibid,  20,  2463;  Overtoil:  Ibid,  26,  19; 
Altschul:  Ibid,  25,  1849. 

18.6  grams  aniline. 

1 60  cc.  hydrochloric  acid  (sp.  gr.  1.19). 

14  grams  sodium  nitrite. 
70  cc.  water. 

50  grams  tin  or  120  grams  stannous  chloride. 
150  cc.  hydrochloric  acid  (sp.  gr.  1.19). 

40  cc.  sodium  hydroxide  (3  cc.  •=  I  gram). 

Prepare  a  solution  of  stannous  chloride  by  dissolving  50  grams 
of  feathered  tin  in  150  cc.  of  concentrated  hydrochloric  acid 
or  by  dissolving  120  grams  of  crystallized  stannous  chloride  in 
100  cc.  of  concentrated  hydrochloric  acid.  Add  18.6  grams  of 
aniline  (i  mol.)  to  100  cc.  of  concentrated  hydrochloric  acid, 
stirring  vigorously.  Set  the  beaker  in  ice-water,  or  a  freezing 
mixture,  and  when  the  temperature  has  fallen  nearly  to  o°,  add 
150  grams  of  ice,  and  then,  from  a  drop  funnel,  drawn  to  a 
narrow  tube  at  the  end,  or  having  a  narrow  tube  attached,  and 
dipping  nearly  to  the  bottom  of  the  solution,  add  slowly  and  with 
constant  stirring,  a  cold  solution  of  14  grams  (i  mol.)  of  sodium 
nitrite  in  70  cc.  of  water.  The  temperature  should  not  rise  above 
5°.  When  all  has  been  added,  the  solution,  after  standing  two 
minutes,  should  react  for  nitrous  acid,  when  a  drop  is  diluted 


DIAZO,    HYDRAZO,    NITROSO,    ETC.  255 

and  tested  with  stacch  potassium  iodide  paper.  If  it  does  not,  a 
little  more  sodium  nitrite  must  be  added,  using  the  least  possible 
excess.  As  soon  as  possible,  add  slowly,  with  stirring,  the  solution 
of  stannous  chloride,  which  must,  meanwhile,  have  been  cooled 
to  o°,  or  below.  Add,  if  necessary,  more  ice,  to  keep  the  tem- 
perature below  o°  during  the  addition  of  the  stannous  chlo- 
ride. Stir  very  thoroughly,  and  allow  to  stand  for  an  hour. 
Filter  off  the  hydrochloride  of  the  phenyl  hydrazine,  which 
separates,  suck  and  press  it  as  free  as  possible  from  the  mother- 
liquors,  and  wash  once  with  a  small  amount  of  dilute  hydro- 
chloric acid.  Evaporate  the  nitrate  to  about  150  cc.>  best 
in  a  large  beaker  heated  over  a  free  flame  on  wire  gauze 
Cool,  and  separate  the  hydrochloride  of  the  phenyl  hydra- 
zine, which  crystallizes,  as  before.  Dissolve  the  hydrochlo- 
ride in  a  small  amount  of  warm  water,  add  an  excess  of  a 
strong  solution  of  sodium  hydroxide,  cool,  collect  the  phenyl 
hydrazine  with  a  little  ether,  separate,  distil  off  the  ether,  dry  by 
allowing  to  stand  in  vacuo  over  sulphuric  acid,  or  dry  with  fused 
caustic  potash,  pour  off  and  distil,  best  under  diminished  pres- 
sure. Some-  ammonia  is  formed  during  the  distillation,  which 
may  be  removed  by  allowing  the  product  to  stand  over  sulphuric 
acid.  The  phenyl  hydrazine  may  be  further  purified  by  a  second 
distillation,  or  by  allowing  it  to  solidify  at  a  low  temperature, 
and  pouring  off  the  liquid  portion.  Yield,  about  18  grams. 

Phenyl  hydrazine  boils  at  242°,  and  solidifies  at  a  low  tem- 
perature, melting  at  19°.  Its  specific  gravity  is  1.097,  at  23°- 
It  is  a  violent  poison.  On  adding  a  solution  of  phenyl  hydrazine 
acetate  to  a  hot  solution  of  copper  sulphate,  it  is  oxidized  with 
the  formation  of  benzene.  With  aldehydes,  ketones,  and  sugars, 
phenyl  hydrazine  gives  characteristic  condensation  products.  See 
PP.  89,  191. 

127.  Preparation  of  a  Derivative  of  Hydroxylamine  by  the  Elec- 
trolytic Reduction  of  a  Nitro  Compound. — /?-Phenylhydroxylamine, 
C6H5NHOH. 

Literature — Brand:  Ber.,  38,  3077;  Bamberger :  Ber.,  27,  1347,  1548; 
Wohl  :  Ber.,  28,  R,  1079  ;  Apparatus  for  electrolytic  reduction,  Brand  : 
Elektro-Chemische  Reduktion  organische  Nitroverbindungen  und  ver- 


256  ORGANIC    CHEMISTRY 

wandter  Verbindungen  ;  Ahren's  Sammlungen,  13,  51;  Elbs :  Uebungsbsp. 
elektrolyt.  Darst.  chem.  Praparate,  Bredt :  Ann.,  366,  13. 

Dilute  sulphuric  acid  (1:20  by  volume). 

50  grams  nitrobenzene. 

20  grams  sodium  acetate. 

15   cc.   glacial  acetic  acid. 

350  cc.  water. 

Wind  a  small  lead  pipe  around  a  porous  cell  having  a  capacity, 
of  750  cc.  and  place  this  within  a  battery  jar  or  porcelain  beaker 
just  wide  enough  to  contain  it.  The  space  between  the  jar  and 
porous  cell  is  to  be  filled  with  dilute  sulphuric  acid  ( i  :2O  by 
volume).  The.  lead  pipe  serves  as  anode  and  the  whole  ap- 
paratus is  kept  cool  by  passing  cold  water  through  it.  For 
cathode  a  piece  of  nickel  gauze  with  a  surface  on  one  side  of 
3  or  4  square  decimeters  is  used.  This  is  bent  in  such  a  man- 
ner that  an  efficient  mechanical  stirrer  (27,  p.  76)  can  play  within 
it  in  the  porous  cup.  Place  in  the  porous  cell  50  grams  of  nitro- 
benzene, 20  grams  of  sodium  acetate,  15  cc.  of  glacial  acetic  acid 
and  350  cc.  of  water.  This  mixture  must  be  kept  thoroughly 
stirred  during  the  passage  of  the  current.  A  current  of  6  to  10 
amperes,  or  of  2  to  3  amperes  per  square  decimeter  of  cathode 
surface  should  be  used.  The  voltage  required  will  depend  on 
the  resistance  but  10  to  12  volts  should  be  enough.  The  cur- 
rent is  best  supplied  by  a  storage  battery,  if  available.  No  hy- 
drogen will  appear  at  the  cathode  till  the  theoretical  quantity 
of  electricity  has  been  used  and  the  current  should  be  broken 
soon  after  that  point  has  been  reached.  One  ampere  of  elec- 
tricity will  furnish  0.000606  gram  of  hydrogen  per  minute. 
Filter  the  cathode  liquid,  wash  out  the  porous  cup  with  a  little 
warm  water  and  add  to  the  united  filtrate  clean,  finely  powdered 
salt  nearly  to  saturation.  The  /?-phenylhydroxylamine  crystal- 
lizes in  long,  silky,  colorless  needles  which  melt  at  81°.  It  may 
be  recrystallized  from  ligroin.  Yield  25  to  30  grams.  Care 
must  be  taken  not  to  bring  solutions  of  phenylhydroxylamine  in 
contact  with  the  skin  as  it  causes  on  some  people  painful  irrita- 
tion and  swelling. 


Chapter  XV 

SULPHUR  COMPOUNDS 

In  the  aliphatic  series  sulphonic  acids  are  obtained  by  the 
oxidation  of  mercaptans  (sulphur  alcohols),  with  nitric  acid,  or 
with  potassium  permanganate. 

RSH  +  30  =   R— S02.OH. 

They  are  also  formed  by  heating  the  sodium  salt  of  an  acid 
ester  of  sulphuric  acid  with  sodium  sulphite  in  concentrated  so- 
lution at  a  temperature  of   i io°-i2o°.( Mayer :   Ber.,  23,  909). 
R— O— SO2— O— Na  +  Na2SO3  =  R— SO2ONa  +  Na2SO4. 

Fatty  acids  react  with  sulphur  trioxide  and  their  anhy- 
drides with  sulphuric  acid,  or  with  the  chloride  of  sulphuric  acid 

/Cl 

SO./  ,  to  form  sulphonic  acids,  which  contain  both  sulphonic 

X)H 

and  carboxyl  groups,  and  are  bibasic.  The  sulphonic  group  usually 
combines  with  the  a-carbon  atom. 

In  the  aromatic  series  sulphonic  acids  are  almost  exclusively 
prepared  by  the  action  of  sulphuric  acid,  sulphur  trioxide,  the 
fuming  acid  or  the  chloride  of  the  acid  on  hydrocarbons  and 
their  derivatives.  The  sulphonic  group  usually  enters  into  the 
para  or  ortho  position  with  regard  to  NH2,  OH,  CH3,  OR,  Cl, 
Br,  and  I,  but  in  the  meta  position  with  regard  to  CO2H,  SO,H, 
COH,  COCH3,  CN,  CC1S,  or  NO,.  As  with  nitration,  homo- 
logues  of  benzene  are  more  easily  sulphonated  than  benzene 
itself.  The  strength  of  the  acid  to  be  used,  and  the  temperature 
vary  with  different  cases,  and  must  be  established  by  trial  with 
small  amounts,  or  by  a  consideration  of  the  conduct  of  analogous 
compounds. 

RH  +  H2SO4  =  R— SO2OH  +  H2O 
RH  +  SO,HC1  =  RSOoCl  +  H26. 

The  sulphonic  acids  are,  in  most  cases,  easily  soluble  in  water, 
and  as  a  large  excess  of  sulphuric  acid  must  be  used  for  their 
17 


258  ORGANIC   CHEMISTRY 

preparation,  it  is  usually-  necessary  to  separate  the  acids  after 
dilution  with  water.  Two  methods  are  commonly  used.  The 
older  method  and  the  one  almost  universally  applicable,  consists 
in  neutralizing  the  diluted  solution  with  calcium  carbonate,  or 
barium  carbonate,  and  filtering  from  the  insoluble  sulphates,  the 
calcium  and  barium  salts  of  the  sulphonic  acids  being  usually 
soluble  in  water.  From  these  salts  the  sodium  or  potassium  salts 
can  then  be  prepared,  by  use  of  sodium  or  potassium  carbonate. 
The  second  method  consists  in  saturating  the  diluted  solution 
with  salt,  which  will,  in  many  cases,  cause  the  precipitation  of  the 
sodium  salt,  even  in  cases  where  the  latter  is  comparatively  easily 
soluble  in  pure  water  (see  p.  159  and  28,  p.  79). 

Sulphonium  compounds  are  prepared  by  treating  alkyl  sul- 
phides with  alkyl  iodides,  or  by  treating  metallic  sulphides  with 
an  excess  of  alkyl  iodide. 

R2S  +  RI  =  R3SI. 

R\ 

Na2S  +  3RI  =  R— SI  +  aNal. 

R/ 

The  sulphonium  hydroxide  can  be  prepared  from  the  iodides, 

or  other  halogen  salts,  by  treatment  with  silver  oxide  and  water. 

These  hydroxides  are  strong  bases,  resembling  the  quaternary 

ammonium  hydroxides,  and  the  iodoso  and  iodonium  compounds. 

The  preparation  of  benzene  sulphonic  acid  and  the  sulphone- 

chloride  and  amide  has  been  given  in  a  previous  chapter,    (p. 

159). 

128.  Preparation  of  a  Sulphonic  Acid  of  an  Amine. — Sulpha- 

/NH2         (i) 

nilicacid,  C6H4^  .     (Paraamino-sulphobenzene.) 

\S02OH    (4) 

Literature — Gerhardt:  Ann.,  60,  310;  Buckton,  Hofmann:  Ibid,  100, 
163;  Limpricht:  Ibid,  *77,  80;  Laar:  Ber.,  14*  1933;  Schmidt:  Ann.,  120, 
132;  Winther:  Ber.,  13,  1941. 

30  grams  aniline. 

90  grams   (50  cc.)  concentrated  sulphuric  acid. 

Put  90  grams  of  concentrated  sulphuric  acid  in  a  small  flask, 
add  in  small  portions,  with  shaking,  30  grams  (30  cc.)  of  aniline, 


SULPHUR  COMPOUNDS  259 

and  heat  in  an  oil-bath  at  i8o°-i9O°  for  four  to  five  hours,  or 
until  a  drop  of  the  solution,  after  diluting,  and  adding  caustic 
soda,  shows  no  separation  of  aniline.  Allow  to  cool,  pour  into 
250  cc.  of  cold  water,  cool,  filter,  and  wash.  Recrystallize  from 
hot  water,  adding  a  little  bone-black:  Yield  30-35  grams. 

Sulphanilic  acid  crystallizes  with  two  molecules  of  water,  in 
rhombic  plates,  which  effloresce  readily.  It  dissolves  in  166  parts 
of  water  at  10°.  It  carbonizes  on  heating  to  28o°-3OO°.  It 

xSO3Na 
forms  no  salts  with  acids.     The  sodium  salt,   C6H4^ 


2H2O,    and   the   barium  salt,     j  C6H4<  |    Ba   -f 

X 


r       /so3 

H 

NHJ 


crystallize  well. 

Sulphanilic  acid  is  used  in  water  analysis  for  the  estima- 
tion of  nitrites  (see  124,  p.  252).  The  sulphonic  derivatives  of 
amines  are  of  great  technical  importance,  since  the  sulphonic 
group  furnishes  the  "auxochrome"  group  necessary  for  dyestufrs 

,KH2    (i) 

(see  p.  245).     Sulphanilic  acid,  metanilic  acid,  C6H4<f  , 

XSOSH  (3) 

and  the  sulphonic  acids  of  a-  and  /?-naphthylamine  are  espec- 
ially used  in  the  preparation  of  azo  dyes. 

129.  Preparation  of  Sulphonechlorides  and  Sulphonamides  by 
the  use  of  the  Chloride  of  Sulphuric  Acid.  —  o-  and  /^-toluene  sul- 
CH, 


phonamides, 


/ 

/ 
\ 


Literature  —  Remsen  and  Fahlberg:  Am.  Chem.  J.,  i,  427;  Claesson 
and  Wallin:  Ber.,  12,  1848;  Noyes:  Am.  Chem.  J.,  8,  176;  Fahlberg,  Pat- 
ents: Ber.,  ig»  R.  374,  471;  Miiller:  Ibid,  12,  1348;  Terry:  Ann.,  169,  27. 

100  grams  sulphuric  acid  monochloride. 

40  grams  toluene. 

Put  in  a  flask  100  grams  of  the  chloride  of  sulphuric  acid, 


260  ORGANIC   CHEMISTRY 

/ci  ' 

SO2<^          ,  place  it  in  cold  water,  and  drop  in  very  slowly,  with 
X)H 

thorough  cooling,  40  grams  of  toluene.  When  all  has  been 
added,  pour  the  solution  "carefully  into  cold  water.  The 
mixed  sulphonechlorides  will  mostly  solidify  after  a  short  time. 
Filter  on  a  plate  with  the  pump,  and  by  the  continuous  ac- 
tion of  the  pump,  and  the  repeated  addition  of  small  amounts 
of  water,  suck  through  so  much  as  possible  of  the  liquid  chlo- 
ride. The  solid  chloride  remaining  is  nearly  pure  paratoluene- 
sulphonechloride,  and  after  thorough  drying  on  porous  porcelain 
it  may  be  kept  in  tightly-stoppered  bottles,  or  it  may  be  converted 
into  the  amide  by  treatment  with  strong  aqua  ammonia. 

Separate  the  liquid  chloride  from  the  solution,  put  it  in  a  test- 
tube  or  small  flask,  and  cool  it  to  — 20°  for  two  hours,  with  a 
freezing  mixture.  Filter  as  quickly  (as  possible,  the  liquid 
chloride  from  the  solid  which  separates,  with  the  aid  of  the 
pump.  Treat  the  liquid  chloride  obtained  in  this  way  with 
a  slight  excess  of  strong  aqua  ammonia,  filter,  and  crystallize 
the  amides  formed  from  hot  water.  In  crystallizing,  treat  the 
amides  with  enough  water,  added  in  small  portions  to  avoid  an 
excess,  so  that  they  barely  dissolve  on  boiling ;  then  cool  to  about 
70°,  and  keep  at  that  temperature  for  some  time.  Most  of  the 
orthoamide  will  separate,  and  on  filtering  it  off,  and  recrystal- 
lizing  once,  it  will  be  pure.  The  amides  which  separate  on  cooling 
the  filtrate  cannot  usually  be  separated  further  by  crystallization, 
but  by  boiling,  for  half  an  hour,  with  potassium  pyrochromate 
(3  parts),  sulphuric  acid  (4^  parts),  and  water  (8  parts),  the 
parasulphonamicle  may  be  oxidized  to  the  sulphamide  of  benzoic 
acid,  while  the  orthoamide  is  partly  destroyed,  and  partly  remains 
unchanged.  By  cooling,  filtering,  washing,  and  boiling  the  resi- 
due with  barium  carbonate  and  water,  the  acid  is  converted 

1  The  chloride  of  sulphuric  acid  can  be  prepared  by  putting  strongly  fuming  or  crys- 
tallized pyrosulphuric  acid  in  a  distilling  bulb,  fitting  a  tube  passing  into  the  acid  to  the 
neck  of  the  bulb  with  a  stopper,  made  by  wrapping  it  with  thick,  soft  asbestos  paper, 
and  passing  in  dry  hydrochloric  acid  gas  while  the  contents  of  the  bulb  is  warmed.  The 
chloride  will  distil  over.  The  arrangement  of  condenser  and  receiver  should  be  similar 
to  that  for  acetyl  chloride  (see  58,  p.  148). 


SULPHUR  COMPOUNDS  26  1 

into  a  salt,  and  en  filtering  hot,  and  cooling,  the  orthoamide  will 
separate.  Yield  of  orthoamide  about  6  grams. 

Toluene  orthosulphonechloride  is  an  oil,  the  parachloride  melts 
at  89°,  and  boils  at  I45°-I46°,  under  a  pressure  of  15  him. 
Toluene  orthosulphonamide  crystallizes  in  octahedral  crystals, 
which  melt  at  155°,  and  dissolve  in  958  parts  of  water  at  9°. 
Tolueneparasulphonamide  crystallizes  in  leaflets,  which  melt  at 
137°,  and  dissolve  in  515  parts  of  water  at  9°. 

The  orthoamide  is   oxidized   by  potassium  permanganate,   in 

faintly  alkaline  solution,  to  benzoic  sulphinide,  C6H4 

("saccharin")  which  is  500  times  as  sweet  as  cane-sugar.  In 
strongly  alkaline  solutions  it  is  oxidized  by  potassium  perman- 
ganate, or  potassium  ferricyanide,  to  the  orthosulphamide  of 

/C02H 

benzoic  acid,    C6H/ 

XSO2NH2 

130.  Preparation  of   a  Sulphonium  Compound.  —  Trimethylsul- 


phonium  iodide,    CH3  —  SI. 
CH3/ 

Literature  —  Oefele:  Ann.,  132,  82;  Cahours  :  Ibid,  i35»  355;  Klinger: 
Ber.,  10,  1880;  15,  881;  Masson  and  Kirkland  :  J.  Chem.  Soc.,  1889,  135; 
Dehn  :  Ann.  Supl.,  4,  106;  Scholler:  Ber.,  7,  1274;  Klinger  and  Masson: 
Ann.,  243,  193;  252,  257;  Brown  and  Blaikie  :  J.  prakt.  Chem.  [2],  23, 
395- 

3  grams  potassium  hydroxide. 

20  cc.  methyl  alcohol. 

0.8  gram  hydrogen  sulphide. 

13  grams  methyl  iodide. 

Put  in  a  200  cc.  flask  3  grams  of  potassium  hydroxide,  and 
dissolve  it  in  20  cc.  methyl  alcohol.  Weigh  on  scales  sensi- 
tive to  one-tenth  of  a  gram,  and  pass  into  the  solution  0.8  gram 
of  hydrogen  sulphide.  Filter  into  a  100  cc.  flask,  connect  with  an 
effective  upright  condenser,  and  pour  in  through  the  latter 


262  ORGANIC   CHEMISTRY 

13  grams  (5^2  cc.)  of  methyl  iodide.  Warm  gently  till  the 
reaction  begins,  and  then  continue  to  boil  gently  for  half  an 
hour.  Pour  off  the  warm  solution  from  the  potassium  iodide 
which  separates.  On  cooling,  the  trimethylsulphonium  iodide 
will  crystallize.  Pour  the  mother-liquors  back  into  the  flask, 
heat  to  boiling,  allow  to  cool  slightly,  and  pour  off  as  before. 
Recrystallize  the  trimethylsulphonium  iodide  once  or  twice  from- 
methyl  alcohol. 

Trimethylsulphonium  iodide  crystallizes  in  prisms,  which  are 
easily  soluble  in  water,  more  difficultly  soluble  in  alcohol.  The 
study  of  the  sulphoniuum  compounds  has  established,  almost 
beyond  question,  the  quadrivalence  of  the  sulphur  in  them. 
Their  study  has  also  rendered  it  probable  that  the  relation  of  the 
groups  to  the  sulphur  is  such  that  no  change  is  produced  in  the 
molecule  when  two  of  the  groups  exchange  places,  or,  as  usually 
stated,  that  the  four  valences  of  the  sulphur  atom  are  of  equal 
value  in  the  same  sense  that  the  valences  of  the  carbon  atom 
are  alike. 

When  four  different  groups  are  combined  with  a  sulphur 
atom,  however,  the  molecule  becomes  asymmetric  and  the  result- 
ing compound  may,  in  some  cases,  at  least  be  separated  into 
optical  isomers,  Pope  and  Peachy:  J.  Chem.  Soc.,  77,  1072. 

CH  — CH 

II  II 

131.  Thiophene — CH       CH. 

\/ 

S 

Literature — V.  Meyer:  Ber.,  16,  1465,  1471;  Ibid,  17,  2641;  18,  217;  V. 
Meyer  and  Sandmeyer :  Ibid,  16,  2176;  Volhard  and  Erdmann :  Ibid,  18, 
454;  Schulze:  Ibid,  18,  497;  Paal  and  Taf  el :  Ibid,  18,  456. 

ioo  grams  phosphorus  trisulphide.1 

100  grams  dry  sodium  succinate. 

Powder   finely   and   mix   together    ioo  grams   of   phosphorus 

1  The  phosphorus  trisulphide  can  be  prepared  by  melting  together,  in  a  Hessian 
crucible,  the  theoretical  amounts  of  dry,  red  phosphorus  and  sulphur.  The  sodium  suc- 
cinate can  be  obtained  by  neutralizing  succinic  acid  with  a  strong  solution  of  sodium 
carbonate  or  caustic  soda,  and  evaporating  the  solution  to  dryness. 


SULPHUR  COMPOUNDS  263 

trisulphide,  and  100  grams  of  sodium  succinate,  dried  thorough- 
ly at  140°.  Put  the  mixture  in  -a  flask  or  non-tubulated  retort, 
which  should  be  filled  only  half  full.  Connect  with  a  condenser, 
which  has  a  distilling  bulb  tightly  fastened  to  its  lower  end  and 
surrounded  with  a  freezing  mixture.  From  the  side  tube  of  the 
distilling  bulb  connect  tubes  leading  out  of  doors  or  to  the  chim- 
ney. Heat  till  the  reaction  begins,  and  then  allow  it  to  proceed 
of  itself  till  completed. 

Distil  the  thiophene  from  the  water-bath,  wash  it  with  a  solu- 
tion of  caustic  soda,  dry  it  with  sodium,  and  distil. 

Thiophene  is  a  mobile,  colorless  liquid,  which  boils  at  84°,  and 
has  a  specific  gravity  of  1.062  at  23 9.  On  warming  a  minute 
portion  of  it  with  isatine  and  concentrated  sulphuric  acid,  a 
bluish  green  color  is  produced.  This  reaction  is  used  to  detect 
thiophene  in  benzene. 


Chapter   XVI 


QUALITATIVE  EXAMINATION  OF  CARBON  COMPOUNDS 

Because  of  the  very  great  number  of  carbon  compounds,  it 
is  impossible  to  give  any  scheme  for  qualitative  examination 
which  is  at  all  general  in  its  application.  In  dealing  with  an 
unknown  substance  or  mixture,  the  first  attempt  should  be  to 
determine  what  elements  other  than  carbon  are  present,  and 
whether  the  substance  is  a  single  one  or  a  mixture.  For  the 
latter  purpose  boiling-points  and  melting-points  are  most  gen- 
erally applicable,  substances  with  a  constant  boiling-point,  and 
with  a  sharp  melting-point,  being  usually  pure,  though  there  are 
some  exceptions.  For  the  determination  of  what  elements, 
other  than  carbon  and  hydrogen,  are  present,  the  method  most 
generally  applicable  consists  in  heating  about  o.i  gram  of  the 
substance  with  i  cc.  of  fuming  nitric  acicl(  sp.  gr.  1.48  at  least) 
at  2oo°-3OO°  for  two  hours,  in  a  sealed  tube  having  a  capacity  of 
20  to  30  cc.  (p.  20).  The  tube  must  be  heavy-walled  and  careful- 
ly sealed,  with  a  capillary  at  one  end.  When  cold,  this  end  is  soft- 
ened carefully  in  the  flame  till  the  gases  blow  out.  The  nitric 
acid  will  contain  sulphur,  phosphorus,  and  arsenic  in  the  form  of 
their  respective  acids,  chlorine,  arid  bromine  partly  in  the  form  of 
hydrochloric  and  hydrobromic  acids,  and  partly  free,  iodine  in 
the  form  of  iodic  (not  hydriodic)  acid,  and  metallic  elements 
in  the  form  of  nitrates.  All  of  these  may  be  detected,  when 
present,  by  means  of  the  usual  qualitative  tests  of  inorganic 
chemistry. 

Another  method,  which  is  much  quicker  and  almost  as  general 
in  its  application  for  non-metallic  elements,  consists  in  heating 
with  metallic  sodium.  Put  in  a  short,  dry  tube  of  hard  glass, 
about  1/20  gram  of  clean  sodium.  Heat  quickly  over  a  small 
flame  till  part  of  the  sodium  is  converted  into  vapor,  and  drop 
straight  down  into  the  tube  one  or  two  drops  of  the  substance, 
if  a  liquid,  or  a  corresponding  amount  if  a  solid.  Allow  to 


QUALITATIVE   EXAMINATION   OF   CARBON    COMPOUNDS         265 

cool,  add  a  little  alcohol  to  dissolve  unchanged  sodium,  then  a 
few  cc.  of  water,  and  filter.  The  solution  may  be  tested  for 
various  elements  as  follows : 

Sulphur,  with  a  silver  coin,  with  a  solution  of  sodium  nitro- 
prusside,  or  with  a  solution  of  lead  acetate  in  sodium  hydroxide. 

Cyanides  (in  absence  of  sulphur),  by  warming  with  sodium 
hydroxide  and  a  small  amount  of  a  mixture  of.  ferrous  and 
ferric  salts,  and  subsequent  acidification  with  hydrochloric  acid, 
when  prussian  blue  wil  be  formed,  if  nitrogen  was  present  in  the 
original  substance.  In  some  cases  metallic  potassium  reacts 
more  readily  than  sodium  for  the  detection  of  nitrogen. 

Chlorine,  with  nitric  acid  and  silver  nitrate ;  if  sulphur  or 
nitrogen  are  present,  it  is  necessary  to  boil  with  nitric  acid 
before  adding  the  silver  nitrate. 

Bromine  and  iodine,  with  hydrochloric  acid,  carbon  bisulphide, 
and  chlorine  water,  or  potassium  nitrite  for  iodine. 

Sulphur  and  nitrogen  together  will  form  a  thiocyanate,  which 
gives  a  red  color  with  ferric  chloride  after  acidifying  with  hy- 
drochloric acid. 

The  following  special  tests  are  also   frequently  useful: 

Nitrogen. — Many  nitrogenous  compounds,  but  not  all  (espec- 
ially not  nitro  compounds),  give  ammonia  when  heated  in  a  small 
tube  with  soda-lime.  The  ammonia  is  best  detected  by  means 
of  moist,  reddened  litmus  paper  in  the  mouth  of  the  tube. 

Halogens. — Make  a  small  loop  in  the  end  of  a  copper  wire,  and 
oxidize  it  by  holding  it  in  the  outer  edge  of  a  Bunsen  flame. 
Cool,  dip  in  a  little  of  the  substance  to  be  tested,  and  hold  in 
the  flame.  The  latter  will  be  tinged  green  if  a  halogen  is  prese-it. 
Halogens  may  also  be  detected  by  igniting  the  substance  with 
pure  quicklime  in  a  tube  of  hard  glass,  dissolving  the  residue 
in  nitric  acid  and  testing  in  the  usual  manner.  In  many  cases, 
also,  by  heating  with  sodium  carbonate  till  carbonization  takes 
place,  adding  some  potassium  nitrate,  and  heating  again  till 
white,  dissolving  in  water,  and  testing  with  nitric  acid  and  silver 
nitrate.  Another  method  is  to  put  0.05  gram  of  the  substance 
in  a  test-tube,  add  one  gram  of  sodium  peroxide  and  heat  till  the 


266  ORGANIC   CHEMISTRY 

mixture  is  white.  Cool,  add  acetic  acid  and  a  little  potassium 
persulphate  and  boil.  Iodine,  if  present,  will  be  expelled  and 
may  be  detected  by  the  color  of  the  vapors  or  by  means  of  car- 
bon disulphide  before  boiling.  After  expelling  the  iodine,  bro- 
mine may  be  liberated  by  adding  dilute  sulphuric  acid  and  de- 
tected by  means  of  starch  potassium  iodide  paper  held  in  the 
vapors.  After  expelling  the  bromine  by  boiling,  chlorine  may  be 
found  in  the  solution  which  remains  by  adding  silver  nitrate. 
(Jannasch:  Ber.,  39,  196,  3655.) 

Having  determined  what  elements  are  present,  and,  if  possible, 
whether  the  substance  under  examination  is  a  single  compound 
or  a  mixture,  and,  in  case  of  mixtures,  having,  if  possible,  sep- 
arated the  constituents,  the  remainder  of  the  examination  will 
consist  mainly  in  the  endeavor  to  obtain  some  idea  of  the  nature 
of  the  substance,  and  then  to  identify  it  as  agreeing  entirely  in 
its  properties  with  some  compound  described  in  the  text-books  or 
handbooks  on  organic  chemistry.  The  following  general  prin- 
ciples will  be  of  service: 

Acids  are,  in  most  cases,  sufficiently  soluble  in  water  to  redden 
blue  litmus,  and  in  almost  all  cases  they  are  soluble  in  ammonium 
or  sodium  hydroxide,'  and  decompose  sodium  carbonate  with 
evolution  of  carbon  dioxide.  Polybasic  acids  are  usually  more 
soluble  in  water  than  monobasic  ones,  and  the  solubility  usually 
decreases  with  an  increase  of  molecular  weight.  The  lead  and 
silver  salts  of  many  acids  are  difficultly  soluble,  and  may  be 
obtained  by  precipitation  from  solutions  of  sodium  or  am- 
monium salts.  The  calcium  salts  of  bibasic  acids  are  often  diffi- 
cultly soluble.  The  substances  most  liable  to  be  mistaken  for  acids 
are  phenols,  some  esters  of  ketonic  acids,  and  acid  amides,  these 
compounds  being,  in  many  cases,  soluble  in  alkalies,  and  pre- 
cipitated again  by  acids. 

Esters  are  identified  by  saponification  by  boiling  with  alkalies 
or  acids,  and  subsequent  determination  of  the  alcohol  and  acid 
from  which  they  are  derived. 

Amides,  imides  and  nitriles  are  also  identified  by  boiling  with 
alkalies  or  acids,  which  decompose  them  with  formation  of  am- 


QUALITATIVE  EXAMINATION  OF   CARBON    COMPOUNDS        267 

monia.     The  derivatives  of  different  acids  differ  very  greatly,  of 
course,  in  the  ease  with  which  they  are  saponified. 

Halogen  derivatives  of  hydrocarbons  are  universally  insoluble 
in  water.  Many  of  them  are  decomposed  by  alcoholic  potash 
with  formation  of  unsaturated  hydrocarbons,  but  the  halogen 
atoms  in  the  nucleus  of  benzene  derivatives  usually  react  with 
difficulty,  if  at  all. 

Nitro  compounds  may  be  reduced  to  amines  by  tin  and  hydro- 
chloric acid.  Most  nitro  compounds  give  yellow  solutions  on 
warming  with  alcoholic  potash.  The  nitro  compounds  them- 
selves are  insoluble,  or  very  difficultly  soluble  in  water.  They 
evolve  no  ammonia,  or  very  little  on  warming  with  soda-lime. 

Amines  are  best  characterized  by  the  formation  of  salts  with 
acids.  The  salts  with  chloroplatinic  (H2PtCl6)  and  chlorauric 
(HAuCl4)  acids  are  frequently,  though  by  no  means  always, 
difficultly  soluble  and  characteristic. 

Aliphatic  amines  and  aromatic  amines  with  the  amino  group  in 
the  side  chain,  react  strongly  alkaline  with  litmus.  Aromatic 
amines,  with  the  amino  group  in  the  nucleus,  do  not  turn  red  lit- 
mus blue.  They  form  well  defined  salts,  however.  To  distin- 
guish primary,  secondary  and  tertiary  amines,  see  p.  160.  Anoth- 
er method  of  distinguishing  them  consists  in  treatment  with  ni- 
trous acid.  Primary  amines  form  alcohols,  or  unsaturated  hy- 
drocarbons, or  diazonium  compounds  which  decompose  with 
water  to  form  phenols.  Secondary  amines  form  nitroso  amines, 
which,  on  solution  in  phenol,  treatment  with  a  little  concentrated 
sulphuric  acid,  subsequent  dilution,  and  neutralization  with 
caustic  potash,  give  a  blue  color.  (Liebermann's  reaction:  Ber., 
7,  248;  Baeyer:  Ibid,  7,  966.)  The  reaction  appears  to  be  due 
to  the  formation  of  a  nitrosophenol  by  the  action  of  the  nitroso- 
amine,  and  a  subsequent  condensation  under  the  influence  of  the 
sulphuric  acid.  Tertiary  amines  do  not  react  with  nitrous  acid. 

When  a  primary  amine  is  warmed  with  a  little  chloroform  and 
alcoholic  potash,  an  isonitrile  is  formed,  which  can  be  recog- 
nized by  its  penetrating  and  exceedingly  disagreeable  odor.  (Hof- 
mann.) 


268  ORGANIC   CHEMISTRY 


R—  NH-C         |    Hg     =     2R—  N=C=S  -f  HgS  +  H2S, 


RNjH2   CyCj      |  ±  3KOH     =     R—  N=C  +  3KC1  +  3H2O. 

When  a  primary  amine  is  treated  with  a  little  carbon  disul- 
phide,  dissolved  in  alcohol  or  ether,  a  salt  of  an  alkyl  dithio- 
carbamic  acid  is  formed. 

//S 
2RNH2  +  CS2     =     R—  HN-C^ 

XSHRNH2 

If,  after  evaporating  part  of  the  alcohol,  the  solution  is 
warmed  with  not  too  much  mercuric  chloride,  or  better  with 
ferric  chloride,  a  mercuric  salt  of  the  dithiocarbamic  acid  is 
at  first  formed,  and  this  is  then  decomposed  with  the  formation 
of  an  isothiocyanate  (mustard  oil)  with  a  characteristic  odor. 


or 


R—  NH—  C  -SHRNH2  -f-  2FeCl3        =    R  —  N=C=S  -f 
RNH2HC1  +  HC1  -f  S  -f  2FeCl2. 

Hydrazo,  azo,  diazonium  compounds,  etc.,  may  usually  be  rec- 
ognized by  their  characteristic  properties,  as  given  in  the  chapter 
on  these  substances  and  in  larger  works. 

Alcohols,  phenols,  and  all  compounds  containing  hydroxyl  react 
with  sodium  with  the  evolution  of  hydrogen.  Some  substances  not 
usually  supposed  to  contain  hydroxyl,  as  aldehydes  and  some  ke- 
tones,  react  in  the  same  manner,  however.  The  formation  of 
an  acetyl  or  benzoyl  derivative  (most  easily  by  the  Schotten- 
Baumann  reaction  when  it  can  be  applied,  pp.  154  and  155),  is 
especially  characteristic  of  alcohols  and  phenols.  It  must  be  re- 
membered, however,  that  primarv  and  secondary  amines  show 
a  similar  reaction. 

Methyl  or  ethyl  alcohol  may  be  detected  in  dilute  aqueous  solu- 
tions, as  follows  :  Distil  10  to  20  cc.  from  100-200  cc.  of  the 
solution.  Put  the  distillate  in  a  smaller  bulb,  and  distil  4  to  6 


QUALITATIVE)   EXAMINATION   OF   CARBON    COMPOUNDS         269 

cc.  To  this  distillate,  in  a  test-tube,  add  dry  potassium  carbon- 
ate till  the  alcohol  separates  on  top.  Transfer  the  upper  layer 
to  a  small  distilling  bulb  by  means  of  a  pipette,  and  determine 
its  boiling-point,  boiling  it  with  a  very  small  flame,  and  using 
a  thermometer  with  as  small  a  bulb  as  possible.  Ethyl  alcohol 
may  be  identified  in  this  manner  in  100  cc.  of  a  one  per  cent. 
solution. 


Fig.  40. 

The  boiling-point  of  a  still  smaller  amount  of  a  substance 
may  be  determined  by  the  method  of  Siwoloboff:  Ber.,  19,  795, 
as  modified  by  Mulliken,  "A  Method  for  the  Identification  of 
Pure  Organic  Compounds/'  p.  222,  or  by  the  method  of  Smith  and 
Menzies:  J.  Am.  Chem.  Soc.,  32,  897.  The  last  method  consists  in 
introducing  a  small  amount  of  the  substance  into  the  small  bulb 
shown  in  Fig.  40,  attaching  the  bulb  to  a  thermometer  immers- 
ing in  a  bath  of  water,  sulphuric  acid  or  other  suitable  material 


270 


ORGANIC   CHEMISTRY 


as  for  a  melting-point  determination  and  heating  till  a  rapid 
stream  of  bubbles  escapes  from  the  mouth  of  the  capillary,  or,  in 
case  the  vapor  dissolves  in  the  liquid  in  the  bath,  till  no  more 
bubbles  of  air  escape  from  the  end  of  the  capillary  tube.  On 


Fig.  41. 

allowing  the  bulb  to  cool  somewhat  the  temperature  of  the  bath 
when  the  stream  of  bubbles  ceases  or  when  the  liquid  commences 
to  rise  in  the  capillary,  is  the  boiling-point.  Mulliken's  apparatus 
shown  in  Fig.  41  is  similar  in  principle  and  has  the  advantage 
that  the  vapor  of  the  compound  does  not  come  in  contact  with 
the  liquid  of  the  bath. 


QUALITATIVE  EXAMINATION   OF   CARBON    COMPOUNDS        271 

Phenols,  and  hydroxy  acids  in  which  the  hydroxyl  is  ortho  to 
the  carboxyl,  give  characteristic  color  reactions  with  ferric  chlo- 
ride in  aqueous,  and  sometimes  in  alcoholic  solutions.  Phenols 
dissolve  in  alkalies  with  the  formation  of  unstable  salts.  The 
alkaline  solutions  of  phenols  are  usually  very  sensitive  to  oxida- 
tion, and  to  the  action  of  the  air. 

Aldehydes  and  ketones  are  usually  most  easily  recognized  by 
the  action  of  phenyl  hydrazine  in  dilute  acetic  acid  solution  (see 
24,  p.  73),  or  the  formation  of  compounds  with  acid  sodium  or 
potassium  sulphite  (see  33,  p.  92).  Hydroxylamine,  and  semi- 
carbazine  may  also  be  used  for  purposes  of  identification  (see 
34,  and  35,  pp.  93  and  95).  Aldehydes  redden  instantly  a  very 
dilute  cold  solution  of  a  fuchsine  salt,  which  has  been  decol- 
orized by  sulphurous  acid  (Caro).  Aldehydes  reduce  a  cold, 
ammoniacal  solution  of  silver  nitrate  (see  p.  91).  (Tollens.) 

Sulphonic  acids  are  usually  easily  soluble,  and  the  salts  are 
mostly  soluble,  and  many  of  them  crystallize  well.  The  most 
important  reactions  of  sulphonic  acids  for  purposes  of  identifica- 
tion are  the  formation  of  sulphonamides  (see  70,  p.  159),  the  for- 
mation of  phenols  by  fusion  with  caustic  potash  (see  28,  p.  78), 
the  formation  of  nitriles  by  distillation  of  a  sodium  or  potassium 
salt  with  potassium  cyanide,  of  acids  by  fusion  with  sodium  for- 
mate, and  the  regeneration  of  the  original  hydrocarbon  by  heat- 
ing in  a  sealed  tube  with  concentrated  hydrochloric  acid,  or  dis- 
tillation with  sulphuric  or  phosphoric  acid  in  a  current  of  sup- 
erheated steam.  (Freund:  Ann.,  120,  80;  Armstrong  and  Mil- 
ler: J.  Chem.  Soc.,  45,  148;  Kelbe:  Ber.,  19,  92). 

Hydrocarbons  are  universally  insoluble  in  water,  and  dilute 
acids.  The  hydrocarbons  of  the  marsh  gas  series  are  nearly  or 
quite  insoluble  in  concentrated  sulphuric  acid  (see,  however, 
Orndorff  and  Young:  Am.  Chem.  J.,  15,  261,  as  to  the  slow  ab- 
sorption of  propane  by  fuming  sulphuric  acid).  Some  of  them 
are  converted  into  nitro  compounds  by  dilute  nitric  acid  (p.  209). 
Unsaturated  hydrocarbons  decolorize  bromine  instantly,  are  ab- 
sorbed by  concentrated  sulphuric  acid  with  the  formation  of  acid 
alkyl  esters  of  sulphuric  acid,  and  reduce  cold,  neutral  solutions 


272  ORGANIC    CHEMISTRY 

of  potassium  permanganate  instantly,  with  separation  of  man- 
ganese dioxide.  Aromatic  hydrocarbons  dissolve  in  concentrated 
sulphuric  acid  with  the  formation  of  sulphonic  acids,  which  re- 
main in  solution  on  dilution.  They  are  converted  into  nitro  com- 
pounds, which  remain  undissolved  on  dilution,  by  concentrated 
or  fuming  nitric  acid,  or  mixtures  of  nitric  and  concentrated 
sulphuric  acids.  Dinitro  and  trinitro  compounds,  which  are 
usually  solids,  are,  as  a  rule,  most  suitable  for  purposes  of 
identification. 

Alkaloids  give  precipitates  with  tannic  acid,  phosphomolybdic 
acid,  potassium  mercuric  iodide,  and  with  iodine  in  an  aqueous 
solution  of  potassium  iodide.  Like  amines  they  usually  give 
characteristic  crystalline  salts  with  chloroplatinic,  chlorauric  and 
picric  acids.  Many  alkaloids  may  be  extracted  from  alkaline 
solutions  by  ether,  benzene,  amyl  alcohol,  chloroform,  or  acetic 
ester.  Most  of  them  give  characteristic  color  reactions  of  var- 
ious kinds.  For  details,  reference  must  be  had  to  some  work  on 
toxicology. 

Reagents 

In  very  many  operations  in  organic  chemistry,  success  depends 
on  the  use  of  reagents  in  definite  quantities,  and  in  almost  all 
cases  it  is  an  advantage  to  know  quite  accurately  how  much  of 
each  substance  is  present.  Students  should  acquire  the  habit, 
therefore,  of  using  solutions  of  known  strength,  and  of  weigh- 
ing or  measuring  the  substances  and  solutions  used.  This  is 
greatly  facilitated  by  knowing  the  strength,  approximately,  of 
the  common  laboratory  reagents,  and  by  having  always  at  hand 
certain  strong  solutions  of  substances  often  used.  Facility  in 
making  quick,  approximate  calculations  of  quantities  reacting,  is 
necessary,  and  this  is  often  aided  by  using  the  number  of  grams, 
or  deci-,  or  centigrams  of  a  body  corresponding  to  its  molecular 
weight. 

Among  the  solutions  which  are  especially  useful  in  organic 
work,  and  which  are  of  strengths  different  from  the  ordinary 
laboratory  reagents,  may  be  mentioned  the  following: 

Hydrochloric  Acid. — Sp.  gr.  i.u.     One  cc.  contains  0.25  gram 


QUALITATIVE   EXAMINATION   OF   CARBON    COMPOUNDS         2/3 

HC1,  or  4  cc.  =  I  gram  HC1.  One  gram  contains  0.224  gram 
HC1.  This  acid  is  aproximated  closely  by  diluting  concentrated 
pure  hydrochloric  acid  with  an  equal  volume  of  water. 

Sulphuric  Acid. — Sp.  gr.  1.55.  One  cc,  contains  I  gram  H2SO4, 
or  i  gram  contains  0.645  H2SO4.  This  acid  is  closely  approxi- 
mated by  diluting  pure  concentrated  sulphuric  acid  with  an  equal 
volume  of  water. 

Sodium  Hydroxide.— Sp.  gr.  1.29.  One  cc.  contains  0.335  gram 
NaOH,  or  3  cc.  =  I  gram.  One  gram  contains  0.26  gram 
NaOH.  The  solution  is  approximated  closely  by  dissolving  335 
grams  of  pure  sodum  hydroxide  in  700  cc.  of  water,  and  diluting 
the  solution  to  one  liter,  when  cold.  The  solution  does  not  at- 
tack glass  as  readily  as  wreaker  solutions. 

Sodium  Nitrite. — 5  cc.  =•  I  gram.  Approximated  by  dissolv- 
ing 205  grams  of  crystallized  sodium  nitrite  in  800  cc.  of  water, 
and  making  the  volume  to  one  liter.  The  exact  strength  can  be 
determined  by  diluting  a  small  portion  very  largely,  acidifying 
with  dilute  sulphuric  acid,  and  titrating  to  permanent  red  with 
standard  potassium  permanganate.  The  end  reaction  is  slow. 

Many  other  solutions  will  suggest  themselves  to  any  one  work- 
ing in  particular  lines,  but  further  details  are  scarcely  necessary. 


1 8 


INDEX 


Page  numbers  in  heavy  face  type  indicate  either  chapter  headings  or  that  directions 
are  given  for  the  preparation  of  the  compound  mentioned.  The  prefixes  para,  ortho, 
etc.,  are  not  regarded  in  the  arrangement;  thus,  ^-nitrobenzoic  acid  is  given  under 
the  letter  N. 

Absolute   ethyl    alcohol,   67. 

Acetaldehyde,   89. 

Acetamide,  156,   157. 

Acetanilide,    157. 

Acetic    acid,    glacial,    acetyl    chloride 

from,  148. 

Acetic  anhydride,   149. 
Acetic  ester,  acetoacetic  ester     from, 

170,  171  ;  drying,  152;  preparation, 


Acetoacetic  ester,  acetic  ester  for 
preparation  of,  152;  collidinedicar- 
boxyllic  ester  from,  240;  condensa- 
tion of  with  itself,  I75J  condensa- 
tion with,  in,  112,  165;  prepara- 
tion, 170;  reactions  for  formation, 
109;  synthesis  of  an  acid  from, 
176. 

Acetone,  chloroform  from,  206;  from 
acetoacetic  ester,  112,  174;  from 
calcium  acetate,  92J  from  distilla- 
tion of  wood,  36;  semicarbazone 
of,  945  test  for,  92. 

Acetonitrile,  157. 

Acetonylacetone,  from  diacetyl  suc- 
cinnic  ester,  176. 

Acetophenone,  phenyl  hydrazone  of, 
100;  reduction  of,  preparation,  73. 

Acetotoluide,   213,  214. 

Acetoxime,   93;    reduction,   226. 

Acetyl  chloride,  148,  149. 

Acetyl  derivative  Of  tartaric  ester, 
156. 

Acetylene,  preparation  from  calcium 
carbide,  47  >  preparation  from 
ethylene  bromide,  49. 


Acetylene   tetrabromide   48, 

Acetyl  group,  oxidation  of,   98,   107. 

Acetylides,  48,  49,  50. 

Acid  amides,  converted  into  amines, 
218,  234. 

Acid  chloride,  a  ketone  by  conden- 
sation of,  101;  preparation  of,  144, 
148. 

Acid    decomposition    of    acetic    ester, 

112,  174;  of  0-ketonic  acids,  176* 
196. 

Acids,  chlorides  of,  144;  decomposi- 
tion of  dibasic,  114;  derivatives  of, 
144;  formation  of  bibasic,  107; 
from  a  halogen  derivative  of  a  hy- 
drocarbon, 139;  halogen  deriva- 
tives of,  196,  203;  identification, 
266;  preparation,  106;  preparation 
by  decomposition  of  bibasic  acids, 
115*  preparation  by  oxidation  of 
an  alcohol,  116;  preparation  from 
an  amine,  108,  131 »  preparation 
from  esters  or  glucosides,  114,  121; 
preparation  of  a  bromine  deriva- 
tive of  an,  203;  reduced  to  hydro- 
carbons, 40;  unsaturated,  reduc- 
tion of,  i34i  136. 

Acid  sodium  sulphite,  double  com- 
pounds with,  59 ;  preparation,  97. 

Acrolein,    70. 

Active  forms  of  mandelic  acid,    169. 

Acyl  anthranilic  nitrile,  preparation 
of  a  quinazoline  from  an,  239. 

Acyl  derivative  Of  an  amine,  157;  of 
a  hydroxy  acid,  156;  of  an  amino 
acid,  preparation,  232. 


276 


INDEX 


Alcohol,  absolute,  67;  by  Barbier- 
Grignard  synthesis,  66,  745  from 
aromatic  aldehyde  by  potassium 
hydroxide,  72;  from  glucose  or 
fructose,  185 ;  from  saponification 
of  an  ester,  152;  preparation  of  an 
acid  by  oxidation  of,  n6;  specific 
gravity  of,  32J  unsaturated,  69;  64; 
from  amines,  64,  7°;  identification, 
268;  oxidation  of,  89,  106,  n6; 
preparation  of  hydrocarbon  from, 
45J  reduced  to  hydrocarbons,  40. 

Aldehyde  ammonia,  91. 

Aldehyde,  condensation  with  amine 
to  leuco  base,  241;  preparation  of 
from  an  a-hydroxy  acid,  166;  86; 
by  Etard's  method,  86;  by  the 
Barbier-Grignard  reaction,  67 ; 
from  a  monochlor  derivative  of 
an  aromatic  hydrocarbon,  96;  from 
glyoxylic  acids ,  88 ;  from  a-hy- 
droxy acids,  87 ;  from  nitro  com- 
pounds, 87;  identification,  271; 
oxidation  of,  106;  reactions  of, 
88;  test  for,  91. 

Alicyclic    compounds,    40. 

Aliphatic  series,  nitro  compounds  of 
the,  209. 

Alizarin,  78;  reduction  to  anthracene, 
61. 

Alkaloids,   identification,  272. 

Alkyl  dithiocarbonic  acid  from  a  pri- 
mary amine,  268. 

Alkyl-sulphonamides,  160. 

Alloxan    from    uric    acid,    163. 

Allyl   alcohol,  69,   115. 

Allyl  amine,  218. 

Auminium  chloride,  o-benzoylbenzoic 
acid  by  means  of,  104;  condensa- 
tion by  means  of,  38,  58,  101,  104; 
preparation,  59J  synthesis  of  hy- 
drocarbons by  use  of,  58. 

Aluminium  hydroxide,  use  in  clear- 
ing solution,  231- 


Amalgam,  magnesium,  113;  sodium, 
i35- 

Amide,  from  an  acid,  156;  from  the 
chloride  of  an  acid,  145,  158,  260; 
from  ammonium  salts  of  acids, 
145;  from  cyanides,  108;  from  es- 
ters, 146;  identification,  266. 

Amine,  dimethyl  and  diethyl  from 
/>-nitrosodimethyl-  or  diethylani- 
line,  220;  acid  amides  converted 
into,  218,  234;  acid  from,  108,  I31; 
acyl  derivative  of,  I57>  converted 
into  alcohols,  64,  7°J  aromatic  con- 
verted into  hydrocarbons,  41  ;  aro- 
matic, from  phenols,  219 ;  by  the 
reduction  of  a  cyanide,  272;  by  re- 
duction of  a  nitro  compound,  220; 
by  reduction  of  hydrazones,  218; 
by  reduction  of  oximes,  218,  226; 
for  dyes,  220 ;  formation  of  sec- 
ondary and  tertiary,  217;  from  an 
alkyl  derivative  of  aniline,  224; 
from  an  oxime,  226;  from  Marsh 
gas  series,  217;  halogen  deriva- 
tives from  the,  195,  201;  identifi- 
cation, 267 ;  nitriles  reduced  to, 
218;  preparation,  217;  preparation 
with' phthalimide,  217;  preparation 
by  use  of  hexamethylene  amine, 
218,  229;  separation  of  primary, 
secondary  and  tertiary,  160 ;  sul- 
phonic  acid  of,  258. 
Aminoacetate,  copper,  231. 

Aminoacetic  acid,  secondary  and  ter- 
tiary, 232;  hippuric  acid  from,  232. 

a-Amino  acid  from  a-amino  nitrile, 
220,  233. 

Amino  acid  from  a  halogen  deriva- 
tive of  an  acid,  231;  preparation 
of  an  acyl  derivative  of  an,  232 ; 
from  the  half  amide  of  a  bibasic 
acid,  234. 

Aminoazobenzene,  245,  250,  251. 


INDEX 


277 


Aminoazo  compounds,  244;  prepara- 
tion of  through  the  diazoamino 
compound,  250. 

2-Aminobenzoic  acid,  234. 

Aminoethanoic  acid,  231. 

i^Aminoethylphen,    101. 

i2-Aminoethylphen,   227. 

Amino  group,  elimination  of,  212;  re- 
placement by  bromine,  201;  re- 
placement by  cyanogen,  13* »  re- 
placement by  hydrogen,  41,  212; 
replacement  by  hydroxyl,  7°»  re- 
placement by  the  ethoxy  group. 
41. 

a-Aminoisobutyric  acid,  233. 

Aminomethylphen,  229. 

Aminonaphthalene  by  reduction  of 
a-nitronaphthalene,  212. 

a-Amino  nitrile  from  an  aldehyde  or 
ketone,  220,  233. 

/>-Amino-o-nitrotoluene,   214,   221. 

2-Aminopropane,  226. 

/j-Amino-sulphobenzene,  258. 

Ammonia,  distillation   of,    18,   19. 

Ammonium  acetate,   156. 

Amyl    alcohol,    oxidation,    116. 

Amyl  nitrite,  use  to  prepare  a  di- 
azonium  compound,  250. 

Anesthetic,  ethyl  bromide  as  an,  198. 

a-   and  ^-Angelica  lactones,   193. 

Anhydride  of  a  bibasic  acid,  150; 
of  an  acid,  144*  *49,  150. 

Anhydrous  keto  ester  from  dihy- 
droxy  compound,  183. 

Anilides,   146. 

Anilinomalonic   ester,   237. 

Aniline,  anilinomalonic  ester  from, 
237;  formation  by  reduction  of  a 
phenyl  hydrazone,  101 :  fractional 
distillation  and  the  determination 
of  boiling-points,  25;  hydrobro- 
mide,  237;  hydrochloride,  251; 
preparation,  220;  ^reparation  of 
an  amine  by  means  of,  244. 
"Aniline  yellow,"  252. 


Anisole,  83. 

Anthracene,  60,   103. 

Anthranilic  acid,  234;  by  reduction 
of  nitrobenzoic  acid,  235;  prepara- 
tion of  indigo  from,  235. 

Anthraquinone,  103;  from  o-benzoyl- 
benzoic  acid,  104;  sulphonic  acid, 
79- 

i.2-Anthraquinonediol,   78. 

Antifebrin,   158. 

Antipyrine,  178. 

Antiseptic,   salicylic   acid,   166. 

Apparatus  for  determination  of 
boiling-points,  Mulliken's,  270 ; 
Smith  and  Menzies',  269;  for  dis- 
tillation with  steam,  71  ;  for  dis- 
tillation under  diminished  pressure, 
171 ;  for  fractional  distillation,  26, 
36;  for  melting-points,  31 ;  for  stir- 
ring, 77J  for  sublimation,  80. 

Aromatic  acid,  preparation  of  a  nitro 
derivative  of  an,  215. 

Aromatic  compounds,  nitro  deriva- 
tives, 209. 

Arsenic  acid  in  Skraup's  synthesis, 
238. 

Arsenic,  detection  in  ethyl  bromide, 
198. 

Autoclave,  use  for  alkali  fusions,  79. 

Auxochrome  groups,  245,  259. 

Azobenzene,  249. 

Azo  compounds,  identifications,  268; 
preparation  from  a  diazonium  com- 
pound, 252,  253;  by  reduction,  244. 

Azo  dyes,  259,  252. 

Azotometer,   calibrating.    13. 

Azoxy   compounds,   2/1/1 

Azulmic  acid,  132. 

Barbier-Grignard    syntheses,    65,    74, 

105. 
Barium,  determination  of  in  salts  of 

organic   acids,   24, 
Barium  nitrate,  oxidation   of  benzyl 

chloride   by,  96- 


278 


INDEX 


Barium  salts  of  nitro  benzole  acids, 
129. 

Barometer,  correction  for,  14. 

Bases,  indicator  for  weak,  254. 

Bath,   Volhard,  53. 

Baumann-Schotten  reaction,  154,  155. 

Beckmann's  mixture  for  oxidizing 
alcohols,  86. 

Beckmann's   rearrangement,    102. 

Benzalacetone,   99,    100. 

Benzaldehyde,  benzyl  alcohol  from, 
72;  condensation  with  acetone,  99J 
condensation  of  with  a  methyl 
group,  100;  condensation  to  ben- 
zoin, 97  J  condensation  with  di- 
methyl aniline,  242;  in  Perkin's 
synthesis,  113,  133;  mandelic  acid 
from,  167 ;  preparation,  96. 

Benzal  chloride,  201. 

Benzamide,   1,61. 

Benzanilide,  102. 

Benzenazomalonic  ester,  247. 

Benzene-azo-a-naphthylamine  s  u  1  - 
phonic  acid,  252. 

Benzene,  bromination  of,  198;  con- 
densation of  an  acid  chloride  with, 
101;  condensation  with  phthalic  an- 
hydride, 104;  diphenyl  from,  56; 
mononitro  compounds  of,  201;  ni- 
tration of,  210,  21 1 ;  nitro  com- 
pounds of  the  homologues  of,  209; 
preparation,  50;  preparation  of  a 
diamino  derivative  of,  223;  reduc- 
tion of,  40,  5°>  sulphonation  of, 
i59'>  test  for,  53. 

Benzene  diazonium  chloride,  249. 

Benzene  sulphonamide,  160. 

Benzene  sulphonechloride,  160. 

Benzidine,  249. 

Benzil  from  benzoin,  97,  98. 

Benzilic  acid  from  benzil,  98. 

Benzoic  acid,  ;benzene_  from,  5°;  by 
oxidation  of  benzyl  chloride,  125, 
201 ;  characteristics  of  ortho  hy- 


droxy    derivatives,     174;    nitration 
of,  216;   o-sulphamide  of,  260,  261. 

Benzoic  ethyl   ester,   153. 

Benzoic  sulphinide,  261. 

Benzoin,  preparation,  97  J  oxidation 
to  benzil,  98. 

Benzonitrile,    161. 

Benzo.phenone,  boiling-point  for  coK 
rection  of  thermometer,  102 ;  pre- 
paration, 101;  reduction  by  hy- 
driodic  acid,  57 »  stereoisomerism 
of  oximes  of,  98. 

Benzoquinone,   77. 

Benzoyl  aminoacetic  acid,  232. 

o-Benzoylbenzoic  acid,  103,  104. 

Benzoylbromanilide,    102. 

Benzoyl  chloride,  benzamide  from, 
i6i»  benzophenone  from,  101;  use 
in  Schotten-Baumann  reaction,  104. 

Benzyl  acetoacetic  ester,  177. 

Benzyl  acetone,  178. 

Benzyl  alcohol,  from  benzaldehyde, 
72;  from  benzyl  chloride,  201. 

Benzyl  amine,  218,  229. 

Benzyl  chloride,  benzaldehyde  from, 
96;  oxidation  to  benzoic  acid,  125; 
preparation,  199. 

Benzyl  cyanide,  228. 

Bibasic  acids,  decomposition  of,  114, 
115;  preparation  of  an  ester  of  a, 
152. 

Bleaching  powder,  preparation  of 
chloroform  with,  195,  206. 

Boiling   capillary,    125. 

Boiling-points,  correction  of  for  pres- 
sure, 29 ;  determination  with  small 
amounts,  269,  270;  o.f  carbon  tetra 
chloride  and  aniline,  25,  27. 

Bromine,  measurement  of,   204. 

Bromination,  204,  205. 

Bromine  derivative  Of  an  acid,  203; 
of  a  hydrocarbon  from  an  aromat- 
ic amine,  201;  of  an  ester,  205; 
of  the  hydrocarbons,  194,  197,  198. 

Bromine,  test  for,  265. 


INDEX 


279 


Bromoform,  92. 
/>-Bromobenzoic  acid,  203. 
Bromobenzoylanilide,    102. 
Bromo-(2)-butanoic  acid,  203. 
a-Bromobutyric  acid,  203. 
Bromoisobutyric  ester,  trimethyl  suc- 

cinnic    acid    from,    112. 
Bromomalonic    acid,    ethyl    ester    of, 

237- 
/>-Bromotoluene,  preparation,  201;   p- 

xylene    from,   55- 
Bruhl's  apparatus,  go. 
Bunsen   pump,   173. 
Bunsen  valve,  182. 
Butane,  chlorination  of,  194. 
Butanoic   acid,   119. 
2-Butanone,  106. 
3-Butanonic  ethyl  ester,  170. 
i,3-Butylonephen,  178. 
Butyric  acid,  bromination,   203;    sep- 
aration   from    propionic    acid,    ng, 

107. 
Cadaverine,    synthesis    of    from    tri- 

methylene  cyanide,  228. 
Calcium  acetate,  37. 
Calcium  chloride,  combination  of  ben- 
zyl alcohol  with,  73;   drying  with, 

26,    117,    127,    170,    207. 
Calcium,    determination    of    in    salts 

of  organic  acids,  24. 
Calcium  hypochlorite,  preparation   of 

chloroform  by,  195,  206. 
Camphoronic    acid,    124. 
Camphor,  oxidation,  123;   preparation 

of  a  hydrocarbon  from,   56. 
a-Camphoramidic     acid,     ammonium 

salt   of,    124,   125. 
j3-Camphoramidic    acid,    sodium    salt 

of,    124,    125. 
Camphoric    acid    by    oxidation    of    a 

cyclic  ketone,  107,  122. 
Camphoric  anhydride,  124. 
Camphoric  imide,  124. 
Cane-sugar,   inversion,    188;    levulinic 

acid   from,   192. 


Carbamide,   158. 

Carbides,  hydrocarbon   from,   47- 

Carbohydrates,  184;  complex  rear- 
rangements produced  in,  185 ;  fur- 
fural from,  190 ;  levulinic  acid 
from,  192- 

Carbon  compounds,  analysis  of,  i ; 
qualitative  examination  of,  264. 

Carbon  tetrachloride,  fractional  dis- 
tillation and  the  determination  of 

boiling-points,    25. 

Carbonyl  chloride,  urea  from,   158. 

Carius*  method  for  determining  halo- 
gens, sulphur  and  phosphorus,  20. 

Cellulose,  184;  solution  of,  189. 

Chapman  pump,  173. 

Chloracetic  acid,  malonic  ester  from, 
136;  preparation  of  indigo  from, 
236. 

Chloral  hydrate,  183. 

Chloride  of  lime,  sodium  hypochlor- 
ite from,  ioo. 

Chloride  of  sulphuric  acid,  prepara- 
tion and  use  in  sulphonation,  260. 

Chlorides  of  acids,   144. 

Chlorination,    direct    of    butane,    194. 

Chlorine  derivatives  of  the  hydrocar- 
bons, 194,  206;  preparation,  200; 
substitution  in  side  chain  of  an 
aromiatic  hydrocarbon,  i99>  test 
for,  265. 

Chlorobenzoic  acid,  85. 

Chloroform,  triphenylmethane  from, 
58;  preparation,  206. 

Chloroplatinic  acid  ("platinic  chlo- 
ride"), salts  with  amines,  227. 

Chromic  acid,  oxidation  with,  89, 
103,  116,  1 19,  260. 

Chromic  anhydride,  oxidation  by,  103. 

Chromophore  group,  183,  245. 

Cinnamic  acid,  from  benzalacetone, 
99;  dibromide,  134;  Perkin's  syn- 
thesis, 113,  i33»  135;  reduction  of, 
134- 


280 


INDEX 


Cinchonine  salt,  crystallization  to 
effect  separation,  169. 

Ciscrotonic  acid,  205. 

Claisen  distilling  bulb,  172. 

Claisen  researches  on  condensation, 
109,  no. 

Collidine,  241. 

Collidinedicarboxyllic  ester,  240. 

Colloidal    solution,    clearing   of,    231. 

Condensation^  by  means  of  aluminum 
chloride,  38,  58,  101,  103;  by 
means  of  zinc  chloride,  142,  242; 
of  acetic  to  acetoacetic  ester,  109, 
i7°»  of  acetoacetic  ester  with  a 
halogen  compound,  176?  of  aceto- 
acetic ester  with  itself,  I75J  of 
acetone  with  benzaldehyde,  99J  of 
an  aldehyde  with  the  sodium  salt 
of  an  acid,  165;  of  an  aldehyde 
with  itself  by  potassium  cyanide, 
97 >  of  a  diazonium  compound 
with  amines  and  phenols,  245,  250, 
252. 

Condensation  products  of  aldehydes 
and  ketones,  88. 

Condenser,   upright,    68. 

Copper  aminoacetate,  231. 

Copper  as  catalyzer,  84. 

Copper  compounds  from  all  deriva- 
tives of  acetylene,  50. 

Corn  cobs,   furfural  from,   190. 

Correction  for  barometer,  14;  of 
boiling-points  for  pressure,  29;  for 
thermometer,  28. 

Coupling  reactions,  245. 

/>-Cresol,  70. 

r/^-Crotonic  acid,  205. 

Crystallization,   fractional,    121,   129. 

Cuprous  bromide,  202. 

Cyanacetic  ester,  I39;  condensations 
with,  112. 

Cyanhydrines,  108;  of  glucose,  185; 
preparation  of  a-hydroxy  acid 
through,  167;  saponified  to  an  ct- 


hydroxy  acid,  164,  167;  prepara- 
tion, 164. 

Cyanides  from  amides,  161;  from  a 
halogen  derivative  of  a  hydrocar- 
bon, 139,  227;  from  aromatic 
amines,  108,  13*1  Ladenburg  meth- 
od of  reduction,  228;  preparation 
of  an  amine  by  the  reduction  of  a, 
227;  saponifkation  of,  107,  108, 
133,  138,  140;  test  for,  265. 

Cyclic  ketones,  86. 

Cyclohexane,  50. 

i.4-Cyclohexanedione,   181. 

Cymene  from  camphor,  40,  56;  from 
geranial,  40. 

Dehydracetic   acid,   174. 

Density,  determination  of,  of  ethane, 
42. 

Determination  of  elements  of  sub- 
stances, 264;  of  specific  gravity, 
32. 

Dextrin,    184,    187. 

Dextrosazone,  191. 

Diacetyl  succinic  ester,   175. 

Di-acetyl  tartaric  ethyl  ester,   154. 

Dialkyl-sulphonamides,    160. 

/>-Diaminobenzene,    223. 

Diastase,    184. 

Diazoamino   benzene,   251. 

Diazoamino  compounds,  245 ;  trans- 
formation into  aminoazo  com- 
pounds, 245. 

/>-Diazobenzene  sulphonic  acid,  253. 

Diazo  compounds,  244. 

/>-Diazonium  benzene  sulphonic  acid, 
252. 

Diazonium  compounds,  246;  azo  com- 
pound from,  250,  252;  cyanide 
from,  131;  discussion  of  decompo- 
sition in  Sandmeyer's  reaction,  202; 
halogen  compound  from,  201;  hy- 
drazine  from,  254;  hydrocarbons 
from,  41,  213;  identification,  268: 
phenol  from,  70;  preparation',  249. 

Diazonium-cuprous  bromide,   201. 


INDEX 


28l 


Diazonium  derivative  of  p.  toluidine, 

201. 
Diazonium  reaction,  use  in  preparing 

a  nitro  compound,  210,  212. 
Dibenzalacetone,   99. 
Dibenzyl,  244;  from  benzoin,  98. 
Dibenzyl  acetoacetic  ester,   177. 
Dibromoallyl  alcohol,  70. 
/7-Dibromobenzene,  198. 
Dibromocinnamic  acid,  134. 
Dibromoethane,  44. 
Diethylamine,  224. 
Diethylammonium   chloride,   225. 
Diethyl  aniline,   225. 
Diethyl  tartaric  ester,  155. 
Dihalogen  substitution  products,  194. 
Dihydrocollidinedicarboxyllic    ester, 

240. 

Dihydroxy  acids,  65. 
Dihydroxy   malonic   acid,    ethyl    ester 

of,  182;   from  uric  acid,  163;   182; 

from  the  green   oxomalonic   ester, 

J83;    dissociation   of,    183. 
Dihydroxyquinone   from   a    sulphonic 

acid,   78. 

Dihydroxyterephthalic  ester,  182. 
Diketohexamethylene,  181. 
4^4-Dimethylaminoazobenzene      s  u  1  - 

phonic    acid,    sodium    salt    of,    253. 
Dimethylaniline,    condensation     with 

benzaldehyde,     242;      condensation 

with    diazobenzene    sulphonic    acid, 

253. 
2,7-Dimethyl-4-hydroxyquinazoline, 

239- 

2,7-Dimethyl-4-ketodihydroquinazo- 
line,    239. 

i.4-Dimethylphen,  54. 

Dimethyl  sulphate,  83. 

?/?-Dinitrobenzene,  211. 

Dinitro  compound,  reduction  of,  221. 

Dinitrotoluene,    preparation    and    re- 
duction,   222. 

Dioximes   Of  benzil,   98. 

Diphenyl,  56. 


Diphenylgycolic  acid  from  benzil,  98. 

Diphenylmethane,  57,  59. 

Diphenylmethanone,  101. 

Diphenylmethanonemethyllic  (2)  acid, 
103. 

Diphenyl  sulphone,   159. 

Dipropylketone,    119. 

Distillation,  fractional,  26,  30,  36,  55, 
127,  157,  172,  200,  206;  of  wood, 
34 »  under  diminished  pressure, 
171;  with  steam,  7X>  117,  128. 

Distilling  bulb,  Claisen,  172;  Hop- 
kins, 19*  Ladenburg,  172. 

Drying  substances,  under  diminished 
pressure,  138;  with  calcium  chlo- 
ride, 26,  197,  117,  127,  198,  207; 
with  potassium  hydroxide,  26,  226, 
228. 

Dye,  amines  for,  220 ;  by  condensa- 
tion of  an  aldehyde,  244;  azo, 
245,  250,  252. 

Dyestuffs,  auxochrome  group  for, 
259;  characteristics,  245. 

Electrolytic  reduction,  136,  255;  of  a 
nitro  compound,  255. 

Elements,   determination,   264. 

Elimination  of  an  amino  group,  212. 

"Enol"  form,  no,  165. 

Enzyme,  preparation  of  a  sugar  by 
action  of  an,  187. 

Eosin,   i43; 

Esterification,  theory  of,  147. 

Esters,  147;  acids  from,  114,  121, 
152;  amides  from,  146;  from  chlo- 
rides of  acids,  148;  from  a  halo- 
gen derivative  of  an  acid,  136; 
identification,  266;  of  a  hydroxy 
acid  and  an  acetyl  derivative, 
154;  preparation,  I51*  ^2,  i53> 
154;  preparation  by  condensation 
by  sodium  ethylate,  170;  saponifi- 
cation  of,  152. 

Etard's  method  for  aldehydes,  86. 
Ethanal,  89. 
Ethanediol,    75. 


282 


INDEX 


Ethane,  preparation  and  determina- 
tion of  density,  42- 

Ethanoic  acid,  ethyl  ester  of,  51 1- 

Ethanoic  anhydride,  149. 

Ethanoyl  chloride,  148. 

Ether,  dry,  82,  175;  extraction  of 
mandelic  acid  with,  167;  phenyl, 
of  salicyclic  acid,  84,  105. 

Ethers,  81. 

Ethyl  acetic  ester,  151. 

Ethyl   alcohol,  absolute,   67. 

Ethyl  benzoate,  triphenyl  carbinol 
from,  74- 

Ethyl  aniline,  225. 

Ethyl  bromide,  197,  198. 

Ethylene,  preparation,  44- 

Ethylene  bromide,  44;  acetylene 
from,  49;  ethylene  cyanide  from, 
140;  glycol  from,  75- 

Ethylene  cyanide,  conduct  on  re- 
duction, 228 ;  preparation,  '  139- 

Ethylene  dibromide,  44. 

Ethylene    glycol,    75. 

Ethylene  series  preparation  of  hy- 
drocarbons of,  44- 

Ethyl  dihydroxymalonate,  priepara- 
tion  of,  182. 

Ethyl  ether,  81. 

Ethyl  oxomalonate,  preparation  of, 
182. 

Ethyl  nitrite,  preparation,   250. 

Ethyl  potassium  sulphate,   198. 

Ethyl  succinic  ester,  152. 

Ethyl  sulphuric  acid,  ethyl  bromide 
from,  198. 

Ethyl  zinc  iodide,  62. 

Extraction  with  ether,  rules,  167, 
1 68,  169. 

Fat,    saponification   of,    121. 

Fatty  acids,  separation  of  two,  119* 
121 ;  sulphonic  acids  of,  257. 

Fehling's  solution  and  its  effect  on 
sugars,  185. 

Ferric  bromide,  used  in  bromination, 
194,  J99- 


Ferric    choride,    color    reaction,    166, 

174- 
Filtration     of     a     hot     solution     for 

crystallization,    181;    with    a    Witt 

plate   or   Hirsch    funnel,    120. 
Fittig's   synthesis    of    hydrocarbons, 

55- 

Fluorescein,    142. 
Formaldehyde,       condensation,       113, 

1 14 ;    hexamethylene    amine    from, 

228. 

Formic  acid,  115;   from  glucose,   193. 
Friedel  and  Crafts  reaction,  38;  ap- 
plication    to     phthalic      anhydride, 

103;    benzophenone    by,     101;     tri- 

phenylmethane   by,   58. 
Fractional  crystallization,  130. 
Fractional  distillation,  26,  30,  36,  55, 

172,  200,  206. 
^'-Fructose,    184. 
Furfural    from    pentoses,    185,    190; 

test  for,   191. 
Furfuramide,    191. 
Furoin,  191. 

Fusel  oil,  oxidation,   n8. 
Gattermann's  reaction,  195. 
Germicide,    iodoform,    208. 
General  operations,  25. 
Geryk    pump,    173. 
Glucoheptonic   acid,    185. 
Glucosazone   from   rf-glucose  and  d'- 
fructose,   185;   preparation,   191- 
rf-Glucose,    184. 
Glucose,  formation  of   levulinic   acid 

from,    185,    192. 
Glucosides,  acids   from,   114. 
Glutaric  acid  and  derivatives,  145. 
Glutaric  ester,   112. 
Glycerol,  allyl  alcohol   from,  69;    use 

in  preparing  formic  acid,  "S- 
Glycocoll,   preparation,   231;    hippuric 

acid  from,  232. 
Glycol,  ethylene,  75- 
Glycolic  acid,  76,  232. 
Glycols,   65. 


INDEX 


283 


Glyoxylic  acids,  aldehydes  from,  88. 
107. 

Grignard-Barbier  synthesis,  65,  74- 

Guano,  uric  acid  from,   162. 

Halogen  alkyls,   194. 

Halogen  compounds,  194;  synthesis 
of  an  acid  by  condensation  of  ace- 
toacetic  ester  with  a,  176;  decom- 
position with  sodium  ethylate,  49 » 
from  the  amines,  195,  201. 

Halogen  derivatives,  identification, 
267;  of  acids,  196,  203. 

Halogens,   determination   of   by   Car- 

ius'  method,  20;  determination  of 
by  Pringsheim's  method,  21 ;  de- 
termination of  by  reduction  with 
sodium  and  absolute  alcohol,  23; 
test  for,  265. 

Halogen  derivatives,  treating,  with 
aqueous  solution  of  ammonia,  217, 
231. 

Hell-Volhard-Zelinsky's  method  of 
preparation  of  a  bromine  deriva- 
tive of  an  acid,  203. 

Helianthine,    253. 

Hempel  column  of  beads,  36. 

4-Heptanone,   106,    119- 

Heptylic   acid,    185. 

Herzfeldt's  formula  for  determining 
sucrose  in  pres'ence  of  other  sug- 
ars, 189. 

Hexamethylene  amine,  use  in  pre- 
paring amines,  218,  229. 

Hexamethylene  compounds  trans- 
formed to  pentamethylene  by  hy- 
driodic  acid,  40. 

Hippuric  acid,   232. 

Hirsch   funnel,    120. 

Hofmann's  reaction  for  preparing 
amines,  219,  234. 

Homoanthranilic  nitrile,  239. 

Hydrazides,  247;   formation  of,  179- 

Hydrazines,  246 ;  preparation  of 
phenyl,  254. 

Hydrazobenzene,   248. 


Hydrazo  compounds,  244;  identifica- 
tion, 268;  preparation  of  a,  248- 

Hydrazones,  amines  by  reduction  of, 
218;  formed,  by  condensation  of 
hydrazines  with  aldehydes  or  ke- 
tones,  246;  by  condensation  of 
diazonium  compounds,  247 ;  of  fur- 
fural, 191 ;  of  mesoxalic  acid,  247. 

Hydriodic  acid,  reduction  of  ketones 
by,  57-  . 

Hydrocarbon,  bromine  derivative, 
197;  bromine  derivative  of  from 
an  amine,  201;  by  the  Barbier- 
Grignard  reaction,  65;  from  car- 
bides, 41,  48;  from  halogen  com- 
pounds and  sodium,  54J  identifica- 
tion, 271 ;  iodine  derivative,  196; 
nitration  of  an  aromatic,  126,  210; 
oxidation  of,  106;  preparation  of, 
38;  preparation  by  reduction  with 
zinc  dust,  60. 

Hydrochloric  acid,  reagent,  272. 

Hydrocinnamic  acid,  by  reduction  of 
cinnamic  acid,  I34J  from  aceto- 
acetic  ester,  176. 

Hydrocyanic  acid,  use  in  benzalde- 
hyde,  97. 

Hydrogen  sodium  sulphite,  double 
compound  of  aldehydes  and  ke- 
tones, 89. 

Hydrogen  sulphide,  reduction  of  a 
nitro  compound  by,  222. 

Hydrolysis  of  a  platosan,  190. 

Hydroxypropylbenzoic  acid,  56. 

Hydroquinone,   76. 

a-Hydroxy  acid  from  an  aldehyde, 
166;  preparation,  108,  J65- 

Hydroxy  acid,  preparation  from  a 
phenol,  165;  ester  and  acetyl  de- 
rivative of,  154;  ortho-  and  para- 
from  phenols,  164. 

Hydroxyanthraquinone  from  phenol 
phthalein,  142. 

Hydroxyazo  compounds,  244. 

o-Hydroxybenzoic  acid,   165. 


284 


INDEX 


/j-Hydroxybenzoic  acid,  166. 

Hydroxybutyric  acid,  205. 

Hydroxylamine,  preparation  of  a  de- 
rivative of,  by  electrolytic  reduc- 
tion of  a  nitro  compound,  255. 

7-Hydroxyvaleric  acid,  193. 

Hypobromite,  sodium,  preparation  of 
pure,  235;  use  in  Hofmann's  reac- 
tion, 236. 

Hypochlorite,  preparation  of  chloro- 
form by  use  of,  206;  action  on  or- 
ganic compounds,  195. 

Imide,  camphoric,   124. 

Imides  f rom  acids,  146 ;  identifica- 
tion, 266. 

Immiscible  solvents,   167. 

Indicator  for  weak  bases,  254. 

Indigo,  preparation  from  anthranilic 
acid,  235;  synthesis  of,  113. 

Indoxyl,  237. 

Indoxylic   acid,   237. 

Inversion   of   sucrose,    185.    . 

Iodides,  reduction  of  to  the  hydro- 
carbon, 39,  42. 

Iodine  derivatives,  195;  of  a  hydro- 
carbon from  an  alcohol,  methyl 
iodide,  196;  of  a  hydrocarbon, 
iodoform,  207. 

Iodine,  test  for,  265. 

Iodoform,   92,    207. 

lodonium    compounds,    258. 

lodoso   compounds,   258. 

Isatine,  test  for  thiophene,  263. 

Isocinnamic  acid,  134. 

Isocyanides,  108. 

Isonitrile,  formation  from  primary 
amine,  267. 

Isonitroso  acetone,  93. 

Isopropyl  amine,  226. 

Isothiocyanate,    formation,    268. 

Isovaleric  acid,  by  oxidation  of  iso- 
amyl  alcohol,  106,  116. 

Ketones,  86;  to  oxidation  of  alco- 
hols, 98;  by  the  Barbier-Grignard 
reaction,  67 ;  by  Friedel  and  Craft's 


reaction,  87,  101;  from  a_hydroxy 
acids,  87;  from  nitro  compounds, 
87 ;  identification,  271 ;  oxidation  of 
106,  119;  oxidation  of  cyclic,  122; 
reactions  of,  88 ;  reduced  to  hy- 
drocarbons, 40,  57- 

Ketonic  acids,  164;   esters  of,  165. 

/3-Ketonic  acids,  decomposition  of, 
112;  acid  decomposition  of,  178, 
196. 

Ketonic  decomposition,  174;  of  ace- 
toacetic  ester,  112. 

KnoevenageFs  synthesis,  113. 

Kohnlein's  method  of  preparing  hy- 
drocarbons, 39. 

Kolbe's  synthesis,  164,  165. 

Kraft's  use  of  sulphonic  acids,  to 
prepare  ether,  81. 

"Kuppelung,"   245. 

Lactone,  angelica,   193;   valero,   193. 

Lactose,  or  milk  sugar,  184. 

Ladenburg's    distilling   bulb,    172. 

Ladenburg's  method  of  reducing  cy- 
anides, 227. 

Law  of  partition  for  immiscible  sol- 
vents, 168. 

Laws  of  substitution  in  aromatic 
compounds,  209,  257. 

Liebig's   condenser,  62. 

Leuco  base,  preparation  by  conden- 
sation of  an  aldehyde,  241. 

Leuco  compounds,  245. 

Levulinic  acid  from  glucose,  185. 
192. 

Levulosazone,    191. 

Liebermann's  reaction  for  identifica- 
tion of  primary  amines,  267. 

Magnesium  acetate,   121. 

Magnesium  bromide  to  purify  ether, 
83. 

Magnesium   ethylate,    113. 

Malachite  green,  241. 

Malonic  acid,  138;  decomposition,  112. 

Malonic  ester,  obtaining  derivatives 
of,  TII;  preparation,  136. 


INDEX 


285 


Maltose,  184,  187. 
Mandelic  acid,  166,  167,   169. 
Mannesmann  tube,  79. 
Manometer,    173;    calibrating,    174. 
Marsh  gas  series,  amines  from,  217; 

nitro   derivatives    of   hydrocarbons 

of  the,  209. 
Melting-points,     correction     for,     28, 

30 ;  determination  of,  29. 
Mesoxalic   acid,   ethyl   ester    of,    182; 

from    alloxan,    163;   hydrazone   of, 

247. 

Metaldehyde,  91. 
Metals,  determination   of,  24. 
Metallic  compounds  from  all  deriva- 
tives of  acetylene,  50. 
Metanilic  acid,  259. 
Methane,  41. 
Methanoic  acid,  115. 
Methine  group,   165. 
Methyl  alcohol,  197. 
3-Methylbutanoic  acid,  116. 
3-Methyl  butanol,  oxidation,    116. 
2-Methylbutanols,    1 18. 
Methylcyanide    from    acetamide,    157. 
Methylene-diethyl    ether,    218,    230. 
Methylene  group,   165. 
Methyl  iodide,  55  ;  action  on  phenyl- 

pyrazolone,    i?9J    preparation,    196- 
/>-Methyl-isopropylphen,    56. 

/j-Methyl   phenol,   70. 

Methyl  orange,  253. 

Methyl  red,   254. 

Mercaptans,  oxidation  of,  257. 

Mercuric  oxide  dissolved  by  solution 

of  acetamide.   157. 
Mesitylene  from  acetone,  40. 
Mesoxalic     acid     ester,     preparation. 

182. 

Mesoxalic  acid  from  uric  acid,  163. 
Monobenzyl  acetoacetic  ester,  177. 
Monobromomalonic    acid,    ethyl    ester 

of,   205. 


Monochloracetic  acid,  aminoacetic 
acid  from,  231;  malonic  ester  from, 
136. 

Monohalogen  derivatives  Of  saturated 
hydrocarbons,  I94J  of  the  ethyl  - 
ene  series,  195- 

"Monohydrate"  sulphuric  acid,  216. 

Monoximes  of  benzil,  98. 

Mordants,   effect   on    alizarin,   80. 

Mulliken's  apparatus  for  boiling- 
points,  270. 

Murexide  reaction,  163. 

Mustard  oils,  268. 

Naphthalene,  nitration  of,  212;  tetra- 
hydride,  40. 

a-Naphthtylamine,   212. 

a_Naphthylamine-azobenzene-/>  -  s  u  1  - 
phonic  acid,  253. 

a-Naphthylamine,  condensation  prod- 
uct from,  252;  sulphonic  acids  of, 
259- 

j3-Naphthylamine,  sulphonic  acids  of, 
259. 

Nickel,  preparation  of  finely  divided 
nickel,  51- 

Nitration,  209;  of  acetanilide,  223; 
acetotoluide,  213;  benzene,  210, 
21 1 ;  benzoic  acid,  215;  naphtha- 
lene, 212;  toluene,  126;  toluidine, 
214;  urea,  94  J  laws  of  position  of 
groups  in,  209;  preparation  of  a 
dinitro  compound  by  direct,  211. 

Nitric  acid,  oxidation  of  benzoin 
with,  98;  oxidation  of  benzyl  alco- 
hol, 125. 

Nitriles   147 ;    formation   of   in   Hof- 

mann's  reaction,  219 ;  *rom  amides, 

161;   identification,  266;  reduced  to 

amines,   218,    229. 

Nitrites,  determination  of  in  potable 

waters,   212. 

/j-Nitroacetanilide  223,  224. 
3-Nitro-4-acetotoluide,  213,  214. 


286 


INDEX 


Nitrobenzene,  210;  azobenzene  from, 
248;  quinoline  from,  238;  reduc- 
tion to  /3-phenylhydroxyl  aminCj 
256. 

Nitrobenzoic  acids,  216. 

ra-Nitrobenzoic  acid,  214,  215. 

o_Nitrobenzoic  acid,  126;  reduction 
of,  235. 

/>-Nitrobenzoic  acid,  126. 

Nitro  compounds,  209;  identification, 
267;  primary,  secondary  and  ter- 
tiary, 210;  reduction  to  an  amine, 

22O,    221. 

Nitro  derivative  of  an  amine,  214; 
of  aromatic  acid,  215. 

Nitrogen  compounds,  derived  from 
amines,  244. 

Nitrogen,  determination  of  by  the 
"absolute"  method,  9 ;  determination 
of  by  the  Kjeldahl  method,  18; 
logarithmic  table  for  reduction  of 
cc.  to  grams,  15;  oxides,  182;  test 
for,  264,  265;  weight  of  in  one 
cubic  centimeter  of  the  gas,  16. 

a-Nitronaphthalene,   212. 

Nitrophthalic   acid,    212. 

Nitrophenols,   210. 

Nitroso  compounds,  244. 

/»-Nitrosodiethylaniline,  diethyl  amine 
from,  220,  225. 

/>-Nitrosodimethylaniline,  dimethyl 
amine  from,  220. 

Nitrosoethyl  aniline,  225. 

Nitrosophenol,  formation,  267. 

/>-Nitrosophenol,  225. 

Nitrotoluenes,    127,    128. 

tw-Nitrotoluene,  212,  214. 

o-  or  />-Nitrotoluene,  oxidation  by 
potassium  ferricyanide,  214. 

3-Nitro-4-toluidine,  213,  214. 

2-Nitro-4-toluidine,  215,  222. 

Nitrourea,  158. 

Nitrous  acid,  test  for,  255. 

"Nitrous  anhydride,"  214. 

Oil  of  bitter  almonds,  96. 


Oleic  acid,   122. 

Optical  isomers  of  sulphonium  com- 
pounds, 262. 

Osazone,  preparation  of  an,  191,  247. 

Oxalic  acid,  decomposition,   114,   115- 

Oxidation  of  a  cyclic  ketone,  122; 
of  an  alcohol  to  an  aldehyde,  89; 
of  an  alcohol  to  an  acid,  116;  of, 
an  alcohol,  to  a  ketone,  98;  of  a 
side  chain,  126;  with  a  chlorate, 
79;  with  a  nitrate,  96;  with  nitric 
acid,  98,  125;  with  potassium  per- 
manganate, 126;  with  sodium  hy- 
ipochlorite,  99 »  with  ,sodium  or 
potassium  pyrochromate,  77>  Il6J 
with  chromic  anhydride,  103. 

Oximes,  amines  by  reduction  of,  218, 
226;  from  benzil,  98;  from  benzo- 
phenone,  102 ;  monobrombenzo- 
phenone,  and  Beckmann's  rear- 
rangement, 102 ;  preparation,  89, 
93- 

Oxomalonic  ester,  182. 

"Oxyazo"  compounds,  245. 

"Oxy"  compounds,  see  hydroxy. 

Palmitic   acid,   122. 

Paraldehyde,  91. 

Pararosaniline  from  triphenylmeth- 
ane,  59- 

Partition  coefficient,  167. 

Penicilium  Glaucum  destroys  levo 
form  to  effect  separation,  170. 

Pentacetyl  glucose,  185. 

Pentamethylene  compounds  from 
hexamethylene,  40. 

2-Pentanone,   106. 

Pentosans,   185. 

Pentoses,  formation  of  furfural 
from,  185,  190. 

Perkin's  synthesis,  113,   133. 

Phen,  50. 

"Phenathylsaure,"  176. 

1 4-Phendiol,    76. 

Phenethylol,  73. 

Phenethylolic  acid,  166. 


INDEX 


287 


Phenmethylol,    72. 

Phenolphthalein,   141,   142. 

Phenols,  64;  aromatic  amines  from, 
219;  from  sulphonic  acids,  64,  78; 
hydroxy  acids  from,  164,  165; 
identification,  268,  270;  phenol 
phthalein  from,  141 ;  preparation 
of  the  benzoyl  derivative  of  a,  I54J 
preparation  through  a  diazonium 
compound,  7°»  reduced  to  hydro- 
carbons, 40,  61- 

Phen-3-propanoic  acid,  134,  176. 

Phenyl  benzoate,   154. 

Phenyl  cyanide,  161;  conduct  on  re- 
duction, 228. 

i  -Phenyl-2,3-dimethyl-pyrazolone,  178. 

/>-Phenylenediamine,  223. 

Phenyl  ether  of  salicylic  acid,  84. 

w-Phenyl-ethyl-amine,  227;  hydro- 
chloride,  229. 

Phenylglycine-o-carboxylic    acid,    236. 

Phenyl  hydrazine,  hydrazones  and 
osazones  from,  247;  hydrazone 
from,  100;  preparation,  254;  89, 
100. 

£-Phenylhydroxylamine,  255. 

Phenylmethylcarbinamine,   101. 

Phenyl  methyl  carbinol,  73. 

Phenyl   methyl   ether,   83. 

i-Phenyl-2,3-dimethyl-pyrazolone,  178. 

i-Phenyl-3-methylpyrazolone,  179. 

Phenyl  propiolic  acid,  134. 

Phenyl  sodium  carbonate,  164. 

Phenyl  sulphonamide,  159. 

Phenyl  sulphonechloride,  preparation, 
159;  use  in  separating  amines,  160. 

Phenyl   xanthenol,    105. 

Phosgene,  urea  from,  158. 

Phosphorus,  determination  of  by  Car- 
ius'  method,  20. 

Phosphorus  oxybromide,  204;  action 
on  acids  and  salts,  decomposition, 
205 ;  to  prepare  succinic  anhydride, 
150. 


Phosphorus  pentachloride,  action  on 
acids  144,  i53>  action  on  ketones, 
195;  action  on  salts,  159- 

Phosphorus  pentoxide,  cymene  from 
camphor  by  means  of,  56;  nitrile 
from  amide  by,  147 ;  to  dry  ether, 
74- 

Phosphorus  trichloride,  action  on 
acids,  144,  148. 

Phosphorus  trisulphide,  use  in  pre- 
paring thiophene,  262. 

Phthalic  anhydride,  anthranilic  acid 
from,  234;  o-benzoylbenzoic  acid 
from,  104;  condensation  of  with  a 
hydrocarbon,  103;  preparation  of  a 
condensation  product  from,  I41- 

Phthalamidic  acid,  234,  235. 

Phthalic  acid,  from  aminonaphtha- 
lene,  212. 

Phthalimide,  234;  use  in  preparing 
amines,  217. 

Pinacone   from  acetophenone,   73. 

Platinum  black,  76. 

Platinic  chloride,  see  chloroplatinic 
acid. 

Polarimeter,  185. 

Polymorphism,   134. 

Polypeptides,  233. 

Potassium  bromide,  ethyl  bromide 
from,  197;  for  Sandmeyer's  reac- 
tion, 201. 

Potassium  cyanide  for  condensation 
of  an  aldehyde,  97- 

Potassium,    determination    of,   24. 

Potassium  ferricyanide,  as  oxidizing 
agent,  214;  oxidation  of  toluene 
sulphonamides  by,  261. 

Potassium  hydroxide  soldtion,  vapor 
pressure  of,  14. 

Potassium  permanganate,  oxidation 
of  nitro  toluene  with,  128;  oxida- 
tion of  unsaturated  hydrocarbon 
to  a  glycol  with  test  for  unsat- 
urated compounds,  135. 


288 


INDEX 


Potassium  phenolate,  hydroxy  ben- 
zoic  acid  formed  with,  164. 

Potassium  phthalimide,  use  in  pre- 
paring amines,  217. 

Potassium  pyrochromate,  separation 
of  o-  and  />-toluenesulphamides  by 
oxidation  with,  260. 

Primary  amines,  test  for,  267. 

Primary  secondary  and  tertiary 
amines,  separation  of,  160,  267, 
carboxyl,  esterification  of,  147;  ni- 
tro  compounds,  210. 

Pringsheim's  method  for  determin- 
ing sulphur  and  halogens,  21. 

Propanoic  acid,  119. 

Propanone,  92. 

Propanone  oxime,  93. 

i,3-Propenol,    69. 

Propionic  acid  separation  from  buty- 
ric acid,  107,  H9' 

Proteins,   synthesis   of,   233. 

"Pseudo"  form  of  benzene  sulphon- 
amide,  161. 

Pyrazolone  derivative,  preparation 
of,  175,  178. 

Pyridine  derivative  from  acetoacetic 
ester,  175,  240. 

Pyridine,  preparation  o>f  a  deriva- 
tive of,  240. ' 

Pyrimidine  compounds  from  aceto- 
acetic ester,  175. 

Pyrogenic  neaction  for  preparing  hy- 
drocarbons, 56- 

Pulfrich  inversion  refractometer,  83. 

Qualitative  examination  of  carbon 
compounds,  264. 

Quinazoline,  preparation  from  an 
acyl  anthranilic  nitrile,  239. 

Quinoid  form  of  phenolphthalein,  142. 

Quinoline,  Skraup's  synthesis  of,  238; 
use  in  preparing  hydrocarbons 
from  halogen  compounds,  39. 

Quinones,  88;  hydroquinone  from,  76; 
from  oxidation  of  a  hydrocarbon, 
103. 


Raikoff  receiver,  182. 

Reaction,  general   for  aldehydes,  91. 

Rearrangement,  Beckmann's,  102. 

Rearrangements  produced  in  carbo- 
hydrates by  dilute  acids  or  en- 
zymes, 185. 

Reagents,  272. 

Reagent,  Schweitzer,   185,   189. 

Receiver,    Raikoff,    182. 

Reducing  agent  for  oximes,  218,  226; 
for  nitro  compounds,  217,  220,  221. 

Reduction  by  alcohol,  132;  ammo- 
nium sulphide,  217,  222;  hydriodic 
acid,  40,  57,  58;  iron  and  acetic 
acid,  217;  nickel,  50;  iodine  and  al- 
cohol, 23,  226,  227;  sodium  and 
moist  ether,  73  >  sodium  amalgam, 
J34J  by  stannous  chloride,  217, 
254*  tin  and  hydrochloric  acid,  217, 
221;  zinc-copper  couple,  42J  zinc 
dust,  60;  zinc  dust,  alcohol  and 
sodium  hydroxide,  248 ;  electrolytic, 
136,  255;  of  a  hydrazone  to  an 
amine,  218;  of  a  hydrocarbon, 
Sabatier's  method,  40,  50,  54;  of  a 
diazonium  compound  to  a  hydra- 
zine,  254;  of  an  oxime  to  an  amine, 
226;  of  a  nitro  compound  to  an 
amine,  220;  to  a  hydrazo  com- 
pound, 248;  to  a  hydroxylamine 
derivative,  255 ;  of  a  ketone  by 
sodium,  73 »  by  hydriodic  acid,  40, 
57J  halogen  compounds  to  deter- 
mine halogens,  23;  of  monohalo- 
gen  derivatives  to  the  hydrocar- 
bon, 39,  42;  of  unsaturated  acids, 
J34,  136. 

Refractometer,  83. 

Replacement  Of  an  amino  group  by 
bromine,  201;  cyanogen,  131;  hy- 
drogen, 41,  213;  hydroxyl,  70. 

Resorcinol,  fluorescein    from,    142. 

Reversed    condenser,   68. 

Rochelle  salt,  use  in  Fehling's  solu- 
tion, 1 86. 


INDEX 


289 


Rotation    of    sucrose    and    of    invert 

sugar,    1 88. 
Sabatier's  method  for  reduction  of  a 

hydrocarbon,  5°- 
Saccharimeter,  185. 
Saccharin,  261. 
Saccharomyces    ellipsoideus    destroys 

dextro    form    to   effect    separation, 

I/O. 

Salicylic  acid,  antiseptic  properties, 
166;  from  sodium  phenolate,  164, 
165;  phenyl  ether  of,  84. 

Sandmeyer  reaction,  108;  for  a  ni- 
tronitrile,  239;  for  halogen  com- 
pounds, 195,  201;  for  preparation 
of  chlorobenzoic  acid,  85. 

Saponification  of  cyanides,  107,  131* 
138,  139;  of  an  ester,  152- 

Schotten-Baumann  reaction,  154,  155, 

1 60. 

Schweitzer's  reagent,  185,  189. 
Secondary    amine,    preparation,    225, 

237;    test   for,  267. 
Semicarbazine,  the  hydrochloride  of, 

95- 

Semicarbazones,  89,  95- 
Separatory  funnel,  127. 
Separation  of  two  fatty  acids,  119, 

121. 

Skraup's  synthesis  Of  quinoline,  238. 

Smith,  Alex,  and  Menzies'  apparatus 
for  boiling-point,  269. 

Soda-lime,  use  to  prepare  a  hydro- 
carbon, 50. 

Sodium  amalgam,  135;  reduction  ot 
an  unsaturated  acid  by,  i34>  135. 

Sodium  anthraquinone  sulphonate, 
79- 

Sodium   benzene   sulphonate,    159. 

Sodium,  determination   of,  24. 

Sodium  ethylate,  condensations  by 
action  of,  no,  170,  176;  acetylene 
by  means  of,  495  properties,  69. 

Sodium  hydroxide,  reagent,  273. 
19 


Sodium  hypobromite,  preparation  of 

pure,    235. 
Sodium  hypochlorite,  oxidation  with, 

99. 

Sodium  nitrite,   reagent,   273. 
Sodium     phenolate,     salicyclic     acid 

formed  with,  164,  165- 
Sodium  pyrochromate,  use  for  oxida- 
tion,  77>  n6. 
Sodium  sulphite,  acid,  preparation  of, 

97- 

Sodium,  wire  Or  small  pellets,  170. 
Solvents,  use  of,   130. 
Specific     gravity,     determination     of, 

32;    of  alcohol,  32. 
Stannous      chloride,      reduction      by 

means  of,  254. 
Starch   potassium   iodide   paper,    test 

for  nitrous    acid,   255. 
Starch,    184. 
Steam  distillation,  71. 
Stearic  acid,    121. 
Stearin,    114. 
Stereochemistry    Of    oximes    of    ben- 

zil,    08. 

Stereoismerism,  98,   134. 
Stilbene,  244. 

Stirring,  apparatus  for,  77. 
Strontium,    determination   of    in    salt 

of  organic  acids,  24. 
Sublimation,  apparatus   for,  80. 
Substitution,    laws    of    in    aromatic 

compounds,   209,   257. 
Succinate,   sodium,   use   in    preparing 

thiophene,  262. 
Succinic    acid,    139;    diethyl  ester  of, 

152;  mono-ethyl  ester  of,  i5x- 
Succinic    anhydride    from    the    acid, 

150. 
Succinic  ester,  succinylosuccinic  ester 

from,    no. 

Succinylosuccinic  ester^  no,  165,  180. 
Sucrose,    (cane    sugar),    184;    deter- 
mination of  specific  rotation,   188; 

inversion  of,  185. 


2QO 


INDEX 


Sugar,  determination  of  the  specific 
rotation  of  invert,  188;  levulinic 
acid  from,  192;  effect  of  Fehling's 
solution  on,  185;  preparation  by 
action  of  an  enzyme,  187;  quanti- 
tative methods  for  determination, 
185. 

Sulphanilic  acid,  azo  compound  from, 
252;  preparation,  258. 

o-Sulphamide  of  benzole  acid,  261. 

/>-Sulphobenzene-azo-a-naphthylamine 
252. 

Sulphonamide,  phenyl,  79  J  toluene, 
259>  preparation  of,  259;  use  in 
separating  amines,  160. 

Sulphonate,  sodium  benzene,  159; 
sodium  anthraquinone,  79. 

Sulphonation,  79,  159,  259. 

Sulphonechloride  of  toluene  from 
chloride  of  sulphuric  acid,  259. 

Sulphonechlorides,  preparation  of, 
i59,  257. 

Sulphone,  diphenyl,  159. 

Sulphonic  acids,  257;  by  oxidation  of 
mercaptans,  257;  from  aniline,  258; 
from  anthraquinone,  795  from  ben- 
zene, 159  i  from  toluene,  259;  iden- 
tification, 271. 

Sulphonium  compounds,  258,   ?6i. 

Sulphonium  hydroxide  from  iodides, 
258. 

Sulphur  alcohols,  257. 

Sulphur  compounds,  257. 

Sulphur,  determination  of  by  Car- 
ius'  method,  20 ;  determination  of 
by  Pringsheim's,  method,  21 ;  quad- 
rivalence  of,  in  the  sulphonium 
compounds,  262;  test  for,  265. 

Sulphuric  acid,  chloride  of,  prepara- 
tion and  use  in  sulphonation,  2,60, 
condensation  by,  105,  141;  "mono- 
hydrate"  or  "absolute,"  215,  216; 
reagent,  272. 

Tallow,    saponification    of,    121. 


Tartaric  acid,  diacetyl  diethyl  ester 
of,  155;  diethyl  ester  of,  I54J  struc- 
ture, 156. 

Terephthalic  acid  from  cymene,  56; 
from  toluic  acid,  133 ;  from  p- 
xylene,  55. 

Tertiary  amines,  test  for,  267. 

Tetrabomflurorescein,  143. 

Tetraldehyde,    91. 

Tetramethyldiaminotriphenylmethane 
242. 

Thiele  apparatus  for  determining 
melting-points,  31. 

Thermometer,   correction   of,   28. 

Thiocarbonic  acids,  derivatives  of, 
268. 

Thiophene,  262. 

Toluene,  p-bromo,  ^-xylene  from, 
55  >  chlorination,  200;  nitration, 
126,  122;  sulphone  chloride  from, 
259- 

o-Toluene  sulphonamide,  259. 

/j-Toluene   sulphonamide,  259. 

o-Toluene  sulphonechloride,  260. 

/>-Toluene  sulphonechloride,  260. 

/>_Toluic  acid,  131,  133;  from  cymene, 
56;  from  /?-xylene,  55. 

/>-Toluidine,  />-acettoluide  from,  213; 
p-cresol,  from,  71 ;  nitration  of, 
214;  ^-tolunitrile  from,  131;  p- 
toluic  acid  from,  131,  132. 

Tolunitrile,   131. 

Trichloromethane,  206. 

Triiodomethane,    207. 

Trimethylene  cyanide,  synthesis  of 
cadaverine  from,  228. 

Trimethyl  succinic  acid  from  bro- 
moisobutyric  ester,  112. 

Trimethylsulphonium   iodide,   261. 

Trinitrotriphenylmethane,  59. 

Triphenyl  carbinol,  74. 

Triphenylchlormethane,  trip  h  e  n  y  1  - 
methyl  from,  60. 

Triphenylmethane,   38,   58. 

Triphenylmethyl,   60. 


INDEX 


291 


Triphenylmethyl  peroxide,  60. 

Tubes,  sealing  of,  20,  156. 

Unsaturated  acids,  reduction  of, 
i34,  136. 

Unsaturated  alcohol,  69. 

Unsaturated  compounds,  permanga- 
nate test  for,  135. 

Upright   condenser,  68. 

Urea,  from  alloxan,  163 ;  from  phos- 
gene, 158;  nitrate  of,  158;  nitro-, 
94 ;  •  to  destroy  nitrous  acid,  72. 

Urethane  obtained,  to  prepare  amines, 

219. 

Uric    acid,    162. 
Urine,  uric  acid  from,  162. 
Vacuum  distillation,  171. 
Valerolactone,  193. 
Vapor  pressure  of  water  and  of  40 

per  cent,  potassium  hydroxide,   14. 
Vinyl   bromide,   49. 
Volatile  liquids,  preservation  of,  175, 

197. 


Volhard  bath,  53. 

Volhard's  method  of  preparing  a 
bromine  derivative  of  an  acid,  203. 

Walker's  method  for  preparation  of 
ethyl  or  methyl  iodide,  197. 

Washing  soluble  substances,  123. 

Water,  vapor  pressure  of,  14. 

Witt  plate,  229. 

Wood,  distillation  of,  34- 

Wood's  metal  for  vacuum  distilla- 
tions, 171. 

Xanthone,   85,    105. 

/>-Xylene,  synthesis,  54- 

Zinc  alkyl  compounds,  hydrocarbons 
from,  39,  63. 

Zinc  chloride,  condensation  by  means 
of,  242. 

Zinc  copper  couple,  zinc  methyl  by 
use  of,  61;  ethane  by  use  of,  42. 

Zinc   dust,   reduction   with,   60. 

Zinc  ethyl,  61. 


oAr;^^SE$;°00so  «NT™ ON  THE  ----- 

OVERDUE.  °N    THE    SEVENTH    DA 


LD  21-95m-7,'37 


/£>// 


THE  UNIVERSITY  OF  CALIFORNIA  LIBRARY 


